I'm considering building a sub using some PVC pipe (4" -6" diameter) from Home Depot, and just casting the nose and tail out of bondo.

My questions are:

1) Will bondo work OK for the nose/tail, or should I use a different material. I know some of you have used it for endcaps on your WTCs. I'm not sure if shrinkage or weight is a problem if I use bondo (I have no experience with it).

2) Do you think that thick wall PVC pipe too heavy for a flooded hull sub? I plan on building a simple dynamic diver with WTCs inside. The kits I've seen have pretty thin plastic shells. I'm guessing if I use the thick PVC pipe, I'll have to add some foam inside the hull to get it to float at the proper level.

3) Where do you place the CG for a cylindrical sub. I'm guessing it should be in the middle, lengthwise, and somewhat below the centerline, height wise, so that it floats upright.

4) Are there any websites that have tips guidelines for designing your own sub (like CG placement, recommended control suface areas, etc.)?

Thanks!