Grayswandir
Senior Member
Regarding support for the underside of your uneven stone,, the only thing I can think of off-hand, is adding a layer of plastic-wrap to the top of your base, then adding a layer of clear silicone-sealant, covered by another layer of plastic-wrap. Place your stone atop the silicon-sandwich, and the sealant will even out and harden, filling in the voids. That would be a water-proof solution, and cheap as well as easy to do. Once it hardens, you can easily trim it with a utility knife. The plastic wrap will prevent the silicone from sticking to the wooden base, and the under-side of your stone. You'll also want to secure the stone so that the top surface of the stone is parallel to the top of the base as the silicone hardens.
That's an interesting idea! I might just try that, sounds like a good way to make the stone sit level in the box.