You have to do a vacuum chamber / pressure pot, even for opaque resins, for small / thin / irregular shaped Transformers parts. When I was learning how to do this stuff, I almost gave up due to how poorly the casts were coming out. Then I finally decided to try a vacuum chamber, and voila, everything looked so much better afterward. Like a lot of other people, I got a cheap paint pot from Harbor Freight and converted it to a pressure pot (there's various vids on youtube about this). You need something that will support 60psi (that's your standard pressure needed for most casts; for certain tasks, you may be able to get away with lower, but you really need 60). You also need to buy a decent air compressor that can easily reach 60psi (should be rated for higher than this). You may need to use vaseline to help cover up any potential tiny air gaps from the lid. Paint pots have a rounded, concave bottom. I've seen people create their own trays to put their molds in the pot. For me, I just poured in some leftover silicone (cheap stuff that I was not planning on using again) to get a flat bottom. The more you use the pot, the more the locking screws will create their own grooves in the lid and shouldn't have leaks. If you end up having just one part of the lid having a leak, you can use a vice grip. You have to get the resin into the pot and up to 60psi before the POT time, so sometimes it feels like a race with quicker setting resins. Otherwise, you'll still end up with bubbles if you wait too long. Some resins though may seem like they set faster than the POT time, though. Leave the resin in the pot until the recommended cure time on the package. At this point, most resins will still not be hard enough to handle. You may be able to demold but this may cause warping. You may need to wait several hours to potentially days depending on the resin used before they harden enough. Clear resins take the longest to harden (5 days). I use a toaster oven to speed up the hardening process after curing, so even clear resins will harden quickly. I usually do not demold until the heating part is done. I place the molds in the toaster oven at 150 degrees for 2 hours. This is enough for relatively small / thin Transformers parts. Going longer or using higher temps on these small parts may cause the mold to get permanently stuck to the resin; ruining both. If you still get bubbles despite this, then you should cut a vertical air vent into the silicone mold to allow for air bubbles to escape and still follow all the same steps. I also use the pressure pot when making the silicone molds to get rid of bubbles instead of a degassing chamber (saw this used on one of Smooth On's demonstration videos). I leave the silicone in the pot until cure time is reached. I get no bubbles in the silicone either. Bubbles in silicone can cause warping and tiny little spikes to appear all over your molds if you have a lot of bubbles.