Step 1: Materials
2 ball bearings
Bike inner tube
4 Chinese take out containers
Spare blocks of wood
Various PVC pipe fittings
1/2 in. conduit pipe
Multi purpose caulk
Heat Shrink Tubing
A lot of my materials were improvised based on what was happening. For instance, I already had pipe, and when I got the bearings, they were different sizes, hence the PVC fittings.
Step 2: PVC Box
Drill a hole the size of your conduit in the middle of 2 rectangles as close to the bottom as you can, allowing space for the bearings. i.e. put the bearing at the bottom of the plexi, and trace the inside of it to know where to drill.
If you don't have the right sized drill bit, go one size up, and make a bushing out of the inner tube.
Be warned that when using any power tools on the plexi, it will start to melt as you go, so you will have to stop frequently.
Use the caulk to glue all but one of the squares together. (so it's a rectangular prism without a top) Book ends are helpful for keeping the pieces in position while they're drying.
Step 3: Water Test 1
Step 4: Paddle Wheels
Step 5: Other Parts
Bushings - You'll want some kind of rubber bushings for it..I used inner tube.
A lid is optional, but recommended.
Heat shrink tubing over the conduit helps with grip.
Styrofoam around the edges help with floatation, and if you glue some in on the insides, it will keep the robot in place. Be sure not to glue all the sides, but make one removable so it will be easier to remove/replace.
Net - I used a pool net for mine. Take a larger piece of pvc, drill a hole in it, put the net in, and stick a screw through the aligned holes. Glue the pvc so that it's about halfway in the water.
Step 6: In the Water
Note for next time: the bushings did have a small leak, the holes for the axles were cut a bit off, and the seal wasn't perfect. I would also try and make the axles treaded, for better traction against the bumpy wheels.