For better control of cooling in specific prints, I use a speed regulator (MFA, Part No 919D2P, available at Maplin's) to manually control the speed of my extruder's fan. This is a simple case I designed for that speed regulator.Dimensions are 72mm x 52mm x 25mm. Box has a 20mm x 6mm window for cables. Version 2 also has 2mm wide slits for ventilation. Fits boards of up to 63mm x 43mm. Top lid just snaps in for most PLA materials I've tried. If not, just rescale it by a bit.