Liquid stone?

 I wonder if there is such a product as liquid stone?

Similar to plaster or cement, which can be mixed and poured at room temperature but not as crumbly. Cement is great for shoe-box size or larger projects, not so good for fiddly little watch or coin sized projects. Plaster is way too fragile, would just crumble.

Epoxy resin is pretty close - mix two liquids and pour, But it's too physically light, doesn't have that "mass" that I'd like. 3D printing is good because you can get all these weird shapes, but a decent printer that does small detail is big dollars. And again - lacks that solid feeling of weight in small projects.

There's a variety of different alloys available which melt at low temperatures, they're good for casting small one-off projects but "low temperature" is a relative term. Plus lead-free alloys are quite pricey - not just to buy, but also in postage. Aluminum would be good as it is easy to save a bunch of cans and off cuts to have "free" raw stock to melt down, but the gases to get the place hot enough to melt and building the furnace (and molds!) is a tad out of my price range.

A material that is a liquid at room temperature, that can be poured into a mold and ends up with the feel and density / mass of a rock or metal would be brilliant. There probably is such a product out there, and it'll be $100 per litre or something stupid.