This is a sliding box I designed to hold a RAMBo board, derived from "Sliding Lid RAMPS 1.4 box" by John Newman.

Some of the pictures show slightly older versions with different hole
configurations on the end.

Print both the box and the lid, slide your RAMBo board in from the right, run your wires through the slots on the left, and slide the lid on top when you're ready to close it all up. The fan can be mounted on the inside or outside, whichever you prefer.

The v1.1b RAMBo board is a biiiiit tighter because of some different surface mounted component on the top, but it still fits. I may update this later to correct that. The only downside is the lid doesn't hold in quite as tight in that case because the box is pressed a bit apart. Once you screw the lid on though it won't matter.