this might be a silly question, but do you have to mold both sides of the gun? It seems a lot of the holsters I'm seeing on here are a front molded panel stitched to a back flat panel (or just slightly molded). I've seen guys do metal casting using fine wet sand. You would take a wooden box filled with the moist sand, put your gun into it (probably wrapped in something very thin unless you have a Glock which can live through anything), smash the sand in tight around it, then extract it. Then you poor your metal into the cast. You would get a good impression, with a flat back side. The materials and setup for this might be cheaper than doing resin casting. I have no idea if it would work or be applicable, but I'm just spit balling. Maybe there are some casters/smiths in here who have some experience. Either way, sometimes it's much more expensive to get into something like this vs. buying the blur gun unless you're doing a bunch of them.