mandrel and a way that would also reduce the risk of having to deal with a stuck mandrel. The above image
illustrates what I came up with. I'm currently making a version of this jig that has several features added in so that I can actually try to cast a grain with this set-up. The most notable features are a star shape on the base that helps seal the bottom so that propellant doesn't seep under and into the core, a hole in the center of the base to ease the installation of the tape, and a secondary top cap which helps to keep everything centered.