DIN slots (DIN 75490/ISO 7736, http://en.wikipedia.org/wiki/ISO_7736 ) for car stereos come in two sizes: single and double height. If a single height device is mounted to a double height slot, the remaining space is usually covered with a useless plastic cover.  I mainly use SD cards, and sometimes USB sticks for sound storage. Disadvantage of miniaturization: they tend to get lost. That's why I wanted to use that space below the car stereo for keeping my media safe.  Two models provided: one for heated beds without additional stuff, one with extra parts to reduce warp. Cut away after print. The second one must be flipped upside down. Both can be printed with exterior support only. Some support has been added to avoid support everwhere mode, the slots bridged well without. Note: printing time up to 10h, depending on your settings. Depeding on warp the outer USB slots may need some work to fit. The front of the part on the pictures has been sanded dry and wet, which gives it a really smooth finish. I don't use all USB slots, so I added a simple clip to plug into one USB slot which can hold a standard hexagonal pencil.