I tried it once years ago.
I used a heavily lubricated condom and plaster of paris to make a mold of my erect cock. But, I had two problems.
First, the plaster became hot and it was uncomfortable. Thank goodness for the condom or I think I would have gotten burned.
Second, it didn't dry fast enough before I started losing my erection and so the outcome was not very good...ie, a bit blurry looking and not detailed.
Johnnlayagrant, how did you do yours so it came out so perfect? And how did you get the balls included also?