Summary

Printable 2-part RAMPS 1.4 case with a slot for a centrifugal fan.
Currently this fits the fan I prised out of my dead Dell D830 laptop, but will make the slot parametric

Instructions

Print and use. Probably best in ABS. Just about prints on my Mendel without the E-motor hitting the bars.
Optionally screw the two parts together with M3 bolts, but it should slide in tightly anyway.
Designed and arranged for easy printing.
In scad file set
explode to 0 to see it together.
railT to change the thickness of the rails
pcbT to change the slot size for the PCB
wT to change the wall thickness
fin to change the size of the lid print support fins

That fan's about 6 bucks from eBay but seems to have some reasonable puff. If anyone has another cheap off-the-shelf suggestion I'll post up the STL for that too. The fan is open both sides, and the recent photo shows a TEC and heatsink topside, which now blows chilled air into the box and gives real kick-ass cooling whilst sucking up some amperage from 5v line of the ATX PSU.

The HP Pavilion DV7 AB7805HX-EB1 looks cheaper, but idk the aperture dimensions

ramps2.stl has feet and cutaway on top right rail for near-the-side board connectors

YARC - Yet Another RAMPS Case