Building raft/dock for show on Pond

[kessie]

My family just moved into a new house on a pond, like with a beach and everything. Pond is large, but extremely shallow, waist-deep 200 yards out. During the summer, the water level rises so I cannot use the sandbar that stretches out like I did in my New Years Show (http://www.youtube.com/watch?v=Chi9l7FA-3s) so I've constructed two fold-up rafts to launch cakes from via remote (QF2x6) one 6-que module per raft. Fold-up because I drive a 2-door coupe... and I don't actually live there, my family does.

I'm having trouble finding a way to float these things [x] (http://i81.photobucket.com/albums/j205/kessie_2006/IMAG2054_zps1b3321d9.jpg)[x] (http://i81.photobucket.com/albums/j205/kessie_2006/IMAG2055_zps5b5e1079.jpg)[x] (http://i81.photobucket.com/albums/j205/kessie_2006/IMAG2058_zpsff5c400a.jpg)[x] (http://i81.photobucket.com/albums/j205/kessie_2006/IMAG2061_zpsdb9f021a.jpg)

What I have to work with so far [x] (http://i81.photobucket.com/albums/j205/kessie_2006/IMAG2064_zps3265f1a7.jpg) And I'm a little uneasy about using duck/duct tape even though it's known to be waterproof, and I only have enough empty gallons for 1 raft/dock.

Any ideas or thoughts on this project?

[JamesFitts]

You can make your own floats with expanding foam. Build a small frame, line it with plastic, and fill half way with foam. It should expand to fill the rest of the mold.