I am trying to make an epoxy part that can be removed from this wheel. It will fill all the holes in the plastic rim. Is there any kind of release agent I can use that will allow the cured part to slide out of the rim?
It depends if the spokes of the wheel taper inwards. If so, this will create a mechanical lock. Regardless of the release agent you use, your mold won’t release.
If the spokes don’t taper, I would use a few (about 4) coats of wax, and a layer on PVA to make sure it will release from the parallel planes of the spokes. You can probably push from the other side of the wheel, this should be plenty of force to push the mould out.
Thanks for the info. They are not tapered, they should be flat/even all the way thru the rim. What kind of wax is best?
Maybe you can consider a silicone mould so that it will release easy with no great concern regarding release angle etc?
I’ve been testing somerelease agents, but I always go back to Meguiars maximum mold release wax #8.
Right now that is way over my head. I really only need one of these. Sounds interesting though, is there any how to threads for that here?
That is actually the cheapest one I found on ebay an bought it. Glad I got the right one:)
Is there any correct way to apply the wax? Maybe a q-tip for inside the plastic rim?
A q-tip is a good idea for the corners. Just apply the wax in a thin layer and leave it on for 10-15 minutes before wiping it of. Doesn’t hurt leaving it on too long.
Great, thanks. So apply the wax, let it sit for 10-15 minutes and repeat 4 more times?
Yes, that’s how I do it when using a mold for the first time. A thin layer of PVA (polyvinyl alcohol) wouldn’t be a bad idea because of the parallel planes in the spokes. If you don’t have PVA or don’t want to buy any, some people have used hair spray as a substitute. I have no experience with this, so you might want to do a quick search before you do this.
The wax arrived extremely quick, I got it today:) I will buy some of the pva online now. Unfortunately I do not have any hair spray. I will have to buy some and start tomorrow.
Success! Feels very strong, should work fine! Thanks again for the help!
looking good 
Here is the finished mount with gear. Thanks again for the help.