We do not yet make the plastic parts for this design, and we thank you for your patience.
The cannon is basically a big tube. The crossbar on which it sits is a toothpick covered by a smaller tube. The platform is a strip with folded edges and a cut-out for the crossbar. The wheels are shown in a single wheel configuration, but if you double them up by stacking two lids together on each side, then the toothpick will more easily maintain a horizontal alignment. The nuts that hold the wheels to the toothpick should be toothpick clips or pierced segments of straw like this (unless you're lucky enough to get a friction-fit to work):
The mechanism that connects the barrel to the crossbar is a bit trickier. I've stuck a toothpick through the crossbar and platform that pierces the tube, which is a bit precarious and difficult to balance.
You'll notice in the examples that I've put a tube within a tube for the barrel. This isn't functional; I just thought at the time that an extendable barrel would be interesting.
If you have rivets, though, the generic version looks a lot spicier. To make it, first remove the top disc from two cans. Poke holes in their center from the inside-to-outside direction, then enlarge them with the punch and then nails until they are large enough to pass rivets with a lot of friction. It should be very difficult to pass the rivet body through, so that it maintains a nice friction-fit while leaving a nice round-tipped spike on the wheel's exterior. Then wrap tape around them to bind the rivet's mandrels together at the desired width.
To make the base, first remove the top of two cans; then remove their bottoms; then cut their sides; and then flatten them out into rectangular sheets. Cut one to an appropriate length and make it into a tube as the Instructions page shows. Fold the other sheet in thirds (leaving the top section a bit short so it doesn't leave an exposed edge) and then run the side of the slider over it to flatten it out again.
Then use the slider to bend the base back on itself with an appropriate gap near the 180-degree turn.
Tape or glue the base back on itself so that it has a nice, flat appearance.
Then insert a rivet through a hole you will make in the base. If you have a rivet gun, you can tighten this one up without breaking the mandrel. Instructions for using rivets and rivet guns are at this link.
Cut an excees square of metal from the neck of the can from when you removed the lid, and form it into a spacer ring, or use a segment of straw, if you want.
Measure how high the barrel will sit above the spacer. Then clip the excess height of the rivet with heavy-duty wire cutters, unless you like the look of the exposed spike.
Poke holes in your barrel using your pushpin/punch so you can pass the toothpick into the base and the front support in the correct vertical alignment. Then pass through the toothpick, position it in the cannon, and see where the toothpick will land on the base. Mark that point with a dent or marker.
