Modular Air Flow Duct/Case

I needed an air flow duct/case around the RAMPS board inside my MendelMax, but none of the existing things seemed to fit. Because there are so many of these cases, it seemed an interesting thought to make a modular version, so it becomes possible to make many kinds of ducts/cases with a single set of components. Attached STL's are for a 60mm fan and RAMPS 1.4 board and my setup. Note that I use a floorboard inside my MendelMax (see thing 28669), so the modules are designed to be screwed to a flat surface, rather than somehow connected to each other.