Taxidermy.Net Forum - cast problems

o.k. i made may cast of my catfish. The first one came out with large holes where the bondo did not totally cover the fish and there were areas that were really thin, and i did not get very good fins at all. So I thought that i didnt mix enough bondo/resin to fill the fish, its a 3lb cat about 23" long and I used one cup of bondo and one cup of resin. On the second cast I doubled the amount and tried to roll the fish around until i figured it had started to kick off. But once again it came out with areas that werent covered and left holes. How much should i be using? I kinda figure it would be a waste of materials to fill the fish completly. Should i fill each half and roll around until the mix starts to kick and then put the halves together? I'm using vasiline thinned down with mineral spirts as a mold release, the casts came out of the mold pretty easy and im pleased with most of the detail that im gettling. I do know i will have to work on the center line of the fish though, i missed it in several places. Also along those lines (pun intended) when i made the mold i made sure that the line of the bed where it met the fish was nice and clean and made the first half but when i flipped him over the belly seemed to bulge over the first cast (kinda like mine does my pants, LOL) is there something i should do so i dont have a bulge on one side of the belly? of the fish that is! Thanks for any help.

Steve