We needed to come up with a way to attach the compartments to the phone case. The first idea was to have hinges on the compartments that corresponded with holes in the back of the case. In the picture above, the red part would be on the container, and the blue part would be inside of the case. However, when we printed this, the parts were too small to hold the pieces together. So, we opted to use a rail idea. The containers have rails on them that slide into slots on the back of the case, so that they can easily slide in and out. The rails had to be small enough to fit inside of the slots, but big enough so that they could be held in place with friction alone.