Next phase: Mold construction. The rules this year just require maximum dimensions for the canoe, so we tried a more streamlined shape than we had last year. This is how we constructed our mold:

We cut tin cross-sections.

We used the tin as a template for cutting foam sections.

We arranged our foam sections on a table.

We sanded the foam, and put putty on it and sanded some more.

We put a Styropoxy coating to keep the concrete from bonding with the foam.

After all of this, our mold was finally ready for concrete.