My bf and I tried the clone-a-willy kits with mixed results. His turned out amazing, the detail that came out was quite intense. Mine, on the other hand didn't work out so well. If your friend does try it out, tell him to use water a little warmer than the directions say so you don't have the same problem as havdisc. Also, it is much much much easier to do with someone else helping, practically a necessity.
We used a cock ring as well and when that didn't work out so well from being nervous, we opted for plan b: impromptu sex which helped
The problem that occurred with mine was more my fault than anything. The mold took and worked, the problem was that I wasn't holding the tube right so I was touching the sides and now my mold is about 1/3 less of what it should have been