I made a simple wagon for my D&D game, the goal wasn't to look as realistic as possible, but to convey the idea of a wagon and be usable as a gaming piece, so the tile structure took precedence. I left a hole in the floor at the front where you can connect a harness connected to pack animals to pull it if you like.

The wheels actually turn if the wheelstops are inserted properly, although that can be finicky depending on your printer's accuracy, so some people may want to opt for just gluing them on.