The biggest mistake I made was not using enough, or the correct, release agent. When I went to take my new creations out of their molds my square one was a block of wood and hypertufa that would not come apart. I took the mold apart and tried to salvage what I could, but the inside of the mold would not come out. My round one (pictured) worked a bit better. I used a margarine container for the inside of the mold and covered it with tufa. The only problem I had with this one was the board I set it on - it did not want to come off. After negotiating with a screwdriver and chisel (and a few threats that I was going to use a hammer) it eventually gave way. I used a wire brush and a file to clean up the edges that the screwdriver messed up a little - and I think it will work fine as a new home for some of my semps.
Thanks again to Tufa Girl for the help in getting started and in clearing up some of the misconceptions I got from other websites.
Stay tuned for Hypertufa - The Next Chapter coming soon!
Get your hands dirty!