Well, if I had access to inert 20mm, 30 mm, 105mm, etc shells, and the means to make the molds, I think there may be a market for war relic “novelties” to be sold in adult bookstores.
It just so happens I’m a 4th generation mold maker working on, believe it or not, some silicone molds for the defense industry.
I could make those molds without any trouble at all.....