I liked caswal's design and give him all the credit. However, I was bothered by the amount of plastic between chambers. This design is my attempt to reduce the thickness of the walls by incorporating magnets as a way to attach the modules.

Printed standard quality. Depending on your printer and materials, you may want to use supports for the square hole. Just be sure to tweak the program so it doesn't build supports in the inside holes or you will have to dig them all out. I did once, and it was kind of a pain. I used 1mm acrylic for the lid which gave me room to print a cover (to keep the queen in the dark) using caswal's design. I used 8mm x 3mm neodymium magnets purchased online.