How to Create a Replacement Tail Light – Moldmaking and Clear Casting Resin Demonstration

How to Create a Replacement Tail Light – Moldmaking and Clear Casting Resin Demonstration

today I’m going to demonstrate how to
mold and cast a car lens using mold star 30 and crystal clear 202 my main
objective for this project is to create obsolete turn lenses from the vehicle
that I’m restoring as I embarked on this project I discovered that the turn
lenses that are broken are not available for purchase anymore so I took that
opportunity to create my own now I went a step further and casted them in a
custom color so the new ones will be yellow instead of the classic orange now
to start with we need a original so because one of the turn signal is broken
we’re going to use the other one that’s still intact to make a detailed mold out
of so that we can cast the reproductions that we need to complete the restoration
of this vehicle and the first step I want to do is I want to set up a bed of
clay I’m going to be using the sulfur free sculptex soft clay and I’m going
to work that clay until it’s nice and even and then separately I’m going to
build up a bed or a pedestal of clay that my turn signal is going to sit on
setting up a model like this has two advantages first it creates a large key
that goes all the way around your model which on the other side is going to
produce a nice and clean casting but it also gives me some space to actually
clean that edge where the model meets the clay furthermore resulting in clean
and precise castings that are going to come out of this mold now before we move
on to the next step I’m going to take a second and wipe down my original model
with some isopropyl denatured alcohol to remove any kind of fingerprints and any
dirt that might be stuck to the model so we don’t transfer that into our mold
now speaking of keys we’re going to put in some keys into the bed of clay that
we set up and for that I’m using these acorn nuts that I simply screwed on to
the back of a bolt mold keys like this are going to help with the alignment of
the two-part mold and are going to help us reproduce precise and clean castings
so the final key that I’m putting in here is orientational key and this key
basically indicates which way the mold goes back together alright now that our
model is fully setup we can proceed to the next step of the mold making
procedure and that is the assembly of a mold box around our model here I’m using
some plexiglass to construct my mold box purely for the visual purposes you can
also use other products such as Gator board, cardboard I’ve used also melamine
board and also wood planks to make my containment box pretty much anything
that’s going to prevent the silicone from leaking out so whenever you work on
a project that is very specific like this you always want to keep the end
result in mind so for my project here I already know that I need a product that
is clear that has UV resistance and I’ve already narrowed down my product search to the crystal clear and according to the Technical Bulletin this product calls
for a very specific silicone rubber so that’s why I’m making my choice to go
with the mold star product now I also want to keep in mind that I want to cast
these with absolutely no air bubbles in them so I already setting myself up
knowing that I will be using a pressure pot for the mold making process as well
as the casting process so something to keep in mind when working with air
compressors and pressure chambers is that there is moisture in the air
compressor tank so two things you can do to avoid this issue one would be to
drain your air compressor tank make sure there’s no water in there
or moisture the other thing you can do is install a dryer right cartridge in
the air line that’s going inside the pressure tank to filter that air and
make sure there’s no moisture trapped in it as you can see here I’m actually pre
mixing the material making sure that there’s no settlement at the bottom
these do separate some one so make sure that you do mix them thoroughly when you
receive the material before you start making your mold and because this is a
one to one mix ratio by volume I can simply mark my measuring containers and
start dispensing and when you do combine them together the Part A and B you want
to make sure you mix thoroughly scrape the sides scrape the bottom of your
mixing container make sure you get a uniform color in your mix there should
be no streaking between the white and the blue should be all uniform color now
I’m going to slowly pour the silicone into our mold box but I’m not going to
pour onto the model directly I’m going to pour in the lowest point of the mold
box and allow the silicone to seek its own level now pouring in a thin stream
like this from a high up allows the entrapped air bubbles to elongate and
break while pouring this is going to further minimize any kind of air trap
meant inside our mold now one quick visual check making sure that we have no
leaks and the first half of our mold can go into the pressure pod well we’ll cure
fully now in order to put the mold inside the pressure pod we have to put
the chamber on its side and put a leveling board in this allowed me to put
a much larger mold inside the pot than what would be possible if the pot was
standing up on its wheels now this pressure pot is available through our
distributors and it also comes with brackets that you can use to secure the
pot on its side like this now when you’re putting the lid on onto the
pressure pod it’s very important to tighten the bolts in a cross order you
can see here I’m starting off at the top right moving on to the bottom left and then I’m going to do the two opposites the same way this is going
to prevent any kind of air leaks once you pressurize your tank now the reason
why we pressurizing the mold and let it cure and the pressure is because there’s
still microscopic bubbles left in the silicone if we were not to do that and
we pressurize our casting to get a perfectly good casting out of it what
happens is those microscopic bubbles will burst and allow the material your
casting material now to be pushed into those cavities resulting in a casting
that’s going to be full of dimples and it’s going to be unusable
I get asked frequently what kind of air compressor people should use for this
application and I found that a 10 gallon or about five horsepower air compressor
would do a sufficient job in producing that 60 psi that we need for this
application something I wanted to mention here is that if you’re looking
for a factory like finish a very clean and bubble-free casting then it’s
absolutely necessary to use a pressure pot like this so if you’re driven by
your results and you’re looking for perfection this is definitely a way to
go the tank is now pressurized and we’re going to let the silicone cure for a
full six hours before proceeding on to the next step now a little shop tip for
you guys that are working in busywork environments it’s a good practice to let
each other know that the pressure chamber is in use so that you’re casting
doesn’t get ruined by somebody needing to use that pressure pod so now the six
hours have passed and the silicone is cured so that we can remove the
containment walls off the mold box you know just strip those away and then
we going to remove all of the clay that we set up our model on and here you can
clearly see the positive keys that resulted in pouring of the material now
that will remove the clay from our model we can proceed to apply
some release agents for the first half of our mold now here I’m using the ease
release 205 which is a liquid version off the ease release 200 and the reason
why I’m doing this is to get a good thorough coverage and piece of peace of
mind so to say some insurance I’m going to go with the liquid version and I’m
going to apply it thoroughly and then we’re gonna let this release agent dry
for about 10 minutes before proceeding to the next step
alright the release agent is dried and we can proceed by reassembling the mould
box around the first half of our mold and something I like to do to prevent
any kind of silicone seeping down below and spilling out is I like to run a beat
of hot melt glue all around the edge where the silicone meets the mold box
for the second half of our mold we’re going to follow the same steps as we did
for the first half of the mold with the dispensing and mixing off the mold star
30 now that we’re pour the second half of our mold we can put the entire piece
back into the pressure pot and let it fully cure for at least 6 hours before
the molding before moving on to the next step so now that our mold has fully
cured we can de molde it and you can hear clearly see the benefits of the
liquid release our two halves came apart with no issues they just peel apart
easily here’s a little tip something that I found works very well for this
type of mold I like to cut a little vent going away from the model but it’s not
really venting all the way out of the mold it’s just collecting off top and
what it does and not only helps the material the excess material evacuate
out of the mold it also creates a little pool of material so in case the casting
means extra material after those air bubbles pop and are evacuated it can
draw from that pool of material it’s going to create a nice and
crisp edge all the way around with minimal defects for the casting of the
lens we’re going to be using the crystal clear 202 and if you look up the
crystal clear series you’ll notice there several of them now the reason why we’re
using the 202 is because it’s designated to work in castings from sixteenth of an
inch to about half an inch and because we have very thin casting this project
kind of demands the crystal clear 202 to be used now I already know that there
will be some extra material that’s going to be squeezed out on the sides out of
our mold because it is a squeezed mold so I’m already anticipating that now to
prevent that material the resin from building up in our pressure pot as a
quick fix I’m simply going to spray some release agent all throughout the pot and
let it dry for about 10 minutes before actually putting any kind of casting
material in it we want to make sure that we protect
ourselves by wearing the appropriate respirator so make sure you read the
technical bulletins and understand the material that you’re working with fully
so I’m now going to dispense my Part B and I’m going to add some so strong
pigment now if you are making multiple pieces you always want to make sure that
you actually write down your amounts of resin and amounts of pigment that you
used so that you can get a consistent color casting every time you mix this is
very important to keep on top in case you’re making multiples or looking for a
specific hue that you’re trying to reproduce now once we have that
pre-mixed early we can go ahead and dispense the Part A and then proceed by
mixing the two components well together keep in mind your pod life off the
product that you’re working with so we have nine minutes to work so we have
plenty of time to mix this thoroughly for this casting I used 95 grams of
crystal clear fifty grams of the Part A and 45 grams of the Part B in addition
to that I add at point two grams of the pigment now I can simply pour the resin
into our mold and proceed by pushing the top of the mold down into it and this is
where the term squeeze mold comes from as you can see I’m squeezing the top
half down and any of the extra material simply spills out seeps out now to
prevent the top of the mold from floating in the material I’m going to
put a heavy brick on it and then put the entire set up into a pressure pot and
let it cure fully at 60 psi and just like we did previously to put that top
of the pressure pot I’m simply going to bolt it down in a cross order or cross
pattern starting at the top right proceeding to the bottom left and do the
opposite sides again this is going to prevent any kind of air leaking while
you have your pot pressurized now we can attach the air hose and
pressurize the tank and allow the casting to cure for about two hours
because the casting thickness the casting walls are so thin I want to give
it some extra time to make sure that I get a good cure on the product now at
this point we can go ahead and remove the air hose from the tank and if we did
a good job on bolting down the lid off that tank the pressure should be
self-contained that you shouldn’t lose any of that pressure now
two hours later I gave this material some extra time because it’s quite thin
in certain sections so I wanted to make sure that it’s absolutely fully cured
once we remove that we can de molde the top half and you can see here any of
the extra material simply peeled away it’s very thin at those edges I can
simply either peel it away or here you can see with a little bit of a scraping
with the exacto knife it’s fully cleaned and ready to be installed now here you
can see the final reproduction of the lens installed on the car that I’m
restoring and as you can tell it works and looks just like the original with
the slight difference that I wanted a yellow tint versus our orange one now if
you got inspired by this project and you’d like to purchase any of these
products you can do so by visiting any one of our distributors around the world
so there you have it a simple and easy way to make a two-part squeeze mold
using the mold star 30 silicone rubber to create some custom color lenses or
lenses that are out of production using some crystal clear 202 and a so strong
pigment now if you have an idea about what we should mold next let me know in
the comments below and if you’d like to see more videos
like this please hit the thumbs up button now to keep up with our latest
mold making and casting videos remember to subscribe

About the Author: Michael Flood


  1. Amazing! Or, you could try your local scrap yard, ebay or a dealer and buy one for $2 – $25. But actually, for an antique or custom car, this might be a viable way to duplicate what might otherwise be unobtainable by any other means.

  2. Nice detailed video! For pressure casting do I have to vacuum mold star 30 first or is it safe to put it in the pressure chamber? I've been hearing very different answers from different sources but from the looks of this video it seems like you just put the mold silicone into the pot without any degassing from vacuum chamber before hand.

  3. This was really great to see because i have been thinking about making some custom lens for my classic Mini.

  4. What process would you do to make the part you are casting dimensionality thicker making it a little more resilient to weather or in case of a marker lense stone damage?

  5. From an R&D toy company design draftsman / prototype guy,,,,,well done ! Great instructions , good product. I personally like slip forms but yours is quick and cheep for a one time shot. thanks for a great video .

  6. How does using a pressure chamber during casting differ to using a vacuum chamber before casting that we see in other youtube videos. The pressure pot seems an easier approach.

  7. Ive always wonder how this was done. I always thought repros were injection molded. I work with resins and now I have the answers to how to replace/fix missing or broken plastic lights,trims etc on vintages. THANK YOU!

  8. Ok that's pretty good , but what would be fantastic is if the new lens was unbrakable or close to unbreakable !

  9. i have a question. Why cant i use a vaccuumchamber instead of the pressurchamber, wouldnt i get rid of the bubbles with this?

    And could you eventually show how to make such parts, but of silicone material. Its always using silicone as a casting material. But what if i would like to produce parts made of silicone? how do i do this? thank you

  10. I have a set of those bumper lights …they look exactly like mine..1986 toyotsa mr2 or trueno, datsun , fx 16gts, complete assembly with plugs in new condition..hit me up if you wanna buy

  11. The reason why it’s orange is because once you put all the white light through it, it turns yellow.
    Those lights won’t even be yellow or orange they’re going to be white because you didn’t make them dark enough.

  12. That yellow is too bright for turn signal in our country, if you use one like that you'll be fked by cops very soon. 😀

  13. How much did that cost, overall? I don't mean, how much, if you figure out how much of the resin, and the silicone, and then how much only that portion would cost. You may only use 5 ounces, but have to buy 16 ounces. What is the REAL cost? For everything…

  14. why a pressure pot?? i would have thought a vacuum chamber would be far more effective at removing air bubbles???

  15. I could really use the amber lens for a 67 dart gt front fender indicators.  they are very small but on my car they are cracked and broken and due to them only being on the 67 they are not reproduced by anyone.  I have the metal housing and the amber pieces but not sure if they are good enough to make a mold of them.   any input would be great.

  16. I need to mold a very small hard but with some flexibility seal.
    What would you recommend ?
    Seal acts as a water stopper for pump spray.

  17. This has nothing to do with this project but how can to remove a lens from the housing on a tail light? I've seen somewhere that they are plastic welded together or something? If I got them apart how do I seal them back? Thanks!

  18. I could save myself lots of money growing large fruit trees if I could make 5,10 and 20 gallon planter molds..🤔

  19. Great video ! How strong is the new cast lens ? I'm guessing it's 1 or 2mm thick ? Wondering how strong or brittle it is

  20. Am paul I live in Uganda in east Africa I wanted to ask u hw to make Lamborghini headlights and hw to do it and the material I use

  21. Could you make a mold casting for a 1/25 convertible model car? It's different from one with a top. My windshield frame is fragile and I don't want to take the chance of breaking it. Heather Smith

  22. Hi,
    Thanks for the amazingly detailed instruction video. Very easy and entertaining to watch.
    Could you tell me how many times you can reuse one silicone mold pair?

  23. It was a lot and only pros. Can do this stuff. im inpressed. I thought it was ez as fiberglass . wow very talented. Congrats.

  24. Hi my question is, why resin remain sticky. I learned by your video and tried also. But my issue is my part is sticking with fingers.
    Can you help me to resolve it.

  25. I want to make my own taillight lenses for my car. I want them to have an OEM shape, but I do not want it to have the OEM defuser texture on the inside of the lense. I want to do a LED conversion and the defuser will not work with it.
    Can you do a video on how this can be done? I would really appreciate it.

  26. I would love to see a video on making wheels for a 1/64th scale car the ones with the rubber tires and plastic wheels the rims with holes all the way through and would be a challenge and it would be nice to see what you recommend for the plastic and the tire I’ve tied many times just haven’t figured it out yet love your videos keep up the good work.

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