You might consider using bolt cutters to cut the wheel weights into
smaller pieces and bagging them like shot bags. Using lead for ballast
where it has to be shifted around can be hard on the insides of a small
boat and the shot bags are a lot more friendly.

For a lunch hook, you can use a one pound coffee can about half full
for ten pounds. I've done it in a BBQ and it works just fine. The
only part that didn't turn out okay was that my eyebolt rusted badly
after using it in salt water.

The waterglass (Sodium silicate, sold in some drug stores) works great
as a mold release and to seal a mold from leakage.

Al Gunther Kingston, WA ---- 47=B0 48.1'N, 122=B0 30.0'W