Also in this class of easy DIY products are thermo plastics like InstaMorph. Its very easy to make small plastic parts for random projects.

That's just InstaMorph! It's simply polyester thermoplastic that is moldable at low temperature (150 degrees Fahrenheit) and solidifies at room temperature. There are other brands with other names, and cheaper than at the amazon link.
That's a fantastic idea, and I actually have some of that stuff. I bought it years ago just to play with it and see what it can do (never needed it though). I'll have to come up with some sort of handle to 'mount' the plastic and stones to though. I'll think of something. Thanks!!!!