So far the stuff is working out pretty good. Time for crappy cell phone pictures!
The original base:
(Yes, those are BBs)
And the copied version:
Its a little tough getting the balls filled with green stuff without air bubbles, but not too bad. It takes a surprising amount of GS to fill a 30 mm base. What I've done with that one was cleaned up the not-quite-full bottom, and then cut the center out of a base and puttied it it.
For those who are wondering, I'm planning ball pit bases for my dreamer crew =oD
I also tried copying one of my brick/cobblestone bases.
Original:
Copy 1:
Copy 2:
For these ones, I put enough GS in to capture the details, and then crammed a base into the hole. One this helped mush everything into the mold, two it used a whole lot less GS, and 3 the tops aren't going to come unglued from the bases.