[Allan] needed a small vacuum chamber to get all the air out of clear casting resin. Degassing is a simple step in casting that improves the finished product immensely. The problem, though, is building a vacuum chamber. [Allan]‘s chamber seems easy enough to build, and pulls enough air out to get to 0.1 atmospheres.
After a hole was drilled in the side of the pressure cooker, [Allan] installed a 15mm “speedfit” plastic tank connector. The seal around the connector is neoprene self-adhesive foam. This foam was also taped around the lip of the pressure cooker for the top.
A thick-walled pressure cooker is more than capable of handling the outside pressure when under vacuum, but [Allan] cautions against using acrylic plastic for the top. Acrylic has the tendency to fail catastrophically, so he used a thick sheet of Lexan. Check out the demo video of [Allan] sucking the air out of shaving cream after the break.