Hello, Pre-pologies if this is an old question. I did my best to search. I've got a large part I'd like to eventually cast in rubber/silicone. Because it's so big, I'm thinking of the following technique: 1.)Print master "positive" in sandstone (for economic reasons) 2.)Create mold of positive using traditional RTV molding techniques 3.)Cast part in silicone. I fully expected destruction of the sandstone master upon de-molding which would be fine, assuming the mold is successful. I'm imagining a pretty much total disintegration at that point...just so long as it holds up until the mold cures! My question here is mostly whether anyone would caution against sandstone as a "positive" material for reasons other than its fragility. Texture-wise, I'm actually hoping for a somewhat rough surface in the casting, so to me sandstone offers that built in Any advice? Thanks in advance, Jared P.S. I'm also hoping to take advantage of the 15% off deal ending tonight, so fast answers will be much appreciated.