garry - I'll ask him, he has all kinds of stuff. He even casts aluminum and lead so there's some other weight options
Susqy- I import the model (an .obj file) into Aspire. I then set up my material, lay out the model (I just laid out the 1 side, then mirrored it to make the second half). Then, you pick your bits. I did 3 cuts, 1 rough cut with a 1/2 bit, then a pocket cut (the dead space around the object, with the same bit. Finally, I did the detail cutting with a 1/16 bit. I probably could have used a 1/8 bit though too. It took about 30 minutes per model to cut.