Hi Chris, I did exactly that, a plaster cast of my breasts, the day before the surgery. I am so happy i did it and the cast hangs in my bedroom. Not painted yet, but draped in a scarf. Its kinda nice, but also kinda sad sometimes. I am so happy I did it though because now I have this beautiful art to remember how I looked before.
I found it very cathartic too, my hubby got involved. I had it done by an artist, quite cheap but she also has kits and will help over the phone. This is my cast on the website.....
http://www.pickledtink.com.au/body-casting/
XXXLouie