1. Arrange the 8 by 8 by 16 blocks on the ground to make a 32- by 54-inch base.
2. Cover with an identical layout of cap blocks.
3. Add layer of firebricks.
4. Cut the barrel in half lengthwise with a hacksaw. Center empty quart can on closed end of a half-barrel; trace and cut out circular shape. This hole will be the vent.
5. Score and cut two firebricks in half with a circular saw (halves measure 4 1/2 inches square).
6. Starting at back end of base, make three U-shaped layers of firebricks to support the half-barrel. Each layer is three bricks long and 2 1/2 bricks wide at back end. Position barrel on bricks.