I saw an artical in EDN Magazine today called “So you want to build an H-bot?”. It describes a cool little light duty method to get XY motion. It is used in pick and place type machines. It uses two motors and one open belt. The belt is fixed at both ends to one end of an axis. The rest is run over idlers. By controlling the directions of the motors, you can move in 2D space. The article does a great job of explaining it. If you both motors in the same direction one axis moves. If they move in opposite directions, the other axis moves.
I thought it would be fun to try it in MakerSlide. This is a just a conceptual drawing with most of the parts free floating where they would be attached with brackets or plates. The two plates in the middle would be firmly bolted together.