This time, I post of adventure with my new Harbor Freight 2.5 gallon pressure chamber which I bought for $98.
It's a poorly constructed affair, with iffy mounts and cheap metal... but it's solid enough to work with and should serve until a better one come available.
This one won't yet sit at 60psi with the hard, badly seated seal that sits there now, but it does well at 40-45psi. As one requires a minimum of around 40psi for decent castings... I am sure this can be improved with a few dollars here and there.
Below is a series of photos showing the mold, which was made with a small Bel-Art vacuum degassing chamber i borrowed for my friend Earl Powell.
This mold used "Smooth-On" Oomoo-30 tin silicone... and I used this carpet tape and modeling clay to seat the parts. The chamber walls are simple scrap polyethylene taped together.
Still the yield was relatively low for a full days casting, and now I see why casters ask SO MUCH for certain jobs.
The clarity and functionality of this process is undeniable and I have been a fool for not breaking down and buying a tank sooner... though I probably still would need a nice compressor if it weren't for TechShops equipment.