Replicating plastic model parts

I have some preliminary results for trying to duplicate some choice plastic parts (in particular, an RB26DETT :D).

Good news: It's do-able! :D :flash:
Bad news: It's time consuming, and the parts are crude, but seem useable. (Imagine a poorly done resin kit.)

Note: wear eye protection.

As a molding agent, I'm using liquid latex rubber. Just paint it on, and let it dry. Paint on just one side, though, so you'll be able to pour ion the casting agent from the other side. This is why the backsides of the parts will be crude. It takes a number of coats to make the mold thick enough to resist warping. The first coat has to be thin, and you have to make sure to blow out ALL of the air bubbles, as these will become positive flash when cast. I use a crappy old brush and the latex cleans up with water. The next coats can be thick and globby. The thicker, the better, because the molds can be reused. You can also embed cotton gauze in the layers of rubber to strengthen the mold further reduce distortion.

As a casting agent, I am using liquid styrene plastic. I remembered a technique I read in a magazine a while back. No heat, all chemical melting. Take a clean empty jar with a lid, dump a good bit of plastic model cement in the jar, then throw in scraps of plastic. I'm using old bits of sprue. This application is about the best use I can think of for the glue that comes in a tube. :hehe: Too bad I already threw mine away. Seal the jar tightly, and let it sit for a day or two.

Like I said, it's time consuming. :rolleyes:

So when the mold is dry and the plastic is melted (stir it up good to make sure), you're ready to go. Peel the mold off the original part, and put the part away in a safe place. My test-piece is the valve cover, because it has lots of fine detail in the lettering and such. Check the mold for any major flaws, i.e. giant bubbles you missed. You should be able to read (in reverse) any writing on the part. Now put the liquid plastic into the mold. I used a simple toothpick for this, but may try an old brush later. I hesitate because the plastic mixture is probably super-toxic. So, stir up the plastic to get a good glob on the toothpick, and smear it into the mold. Then, same drill as before, get all the bubbles out. This time they'll make negative flash: tiny holes in your part. That's a bad thing. It is not easy to fix. Drag the toothpick all around the details in the mold to chase the bubbles out. I don't recommend blowing on it for fear of melted plastic flying back into your eyes and face. Once you think you've chased away all the offensive little bubbles, set it aside where the cat/dog/kid/girlfriend/wife/etc... won't meddle with it. In a covered place, if possible. It'll take about a day to dry and harden.

Like I said, it's time consuming. :rolleyes: ;)

Once it's hardened, you'll see the plastic shrinks way down into a very thin layer. This may be because I mixed too much glue with not enough plastic; further tests to come... I will also be testing the effects of just adding more layers of liquid plastic. In the meantime, I'm using white glue to reinforce the backside of the part. Then, just peel it out of the mold and admire your work.

But, this is a continuing process. I'll keep you guys posted. :D

Blimey!!!:eek:
All hard work that should be spent building the flippin' model!
but whatever makes you happy!!!:rolleyes:

Interesting though! keep us posted, though you have written enough to put me off!!!

haha.. i tried that... long ago, after spenting hours and hours of hard work, i deicided to buy another kit for the extra part..haha..

it just looks so beat up still after hours and hours of work.. :o
specially if you compare it to the original part.. oh man :bloated:

or actually, I know the store owner of the local hobby shop pretty well, and he can help me order just parts of a model kit sometimes .. pretty nice guy :cool:

I'd be real interested to compare notes with how you did it.

Honestly, I don't want three R32 Skyline kits just for the engines. The wheels would be nice, but not nice enought to use them on everything... :)

I tried what you did, and actually was not able to replicate anything.. result turned out terrible... I think I didn't mix the plastic well enough..

so after that, if I'm REALLY REALLY in need of 2 of a same part, I try to make it from scratch from Tamiya Epoxy Putty.. i swear man.. those things does wonders :)

Originally posted by pkw1
so after that, if I'm REALLY REALLY in need of 2 of a same part, I try to make it from scratch from Tamiya Epoxy Putty.. i swear man.. those things does wonders :) No, I think that's just due to your exceptional sculpting skill! :D

Originally posted by Silver S2000
No, I think that's just due to your exceptional sculpting skill! :D :D :D :smoker2: