I wanted to cool my stepper motors after feeling how hot they were getting while printing. The ones I were finding to fit NEMA 17's only cooled one or two sides or they wouldn't work for me because of the tight spots they had to fit into. I found stepper coolers similar to the one I designed but they were meant for the larger NEMA motors and resizing was not a good option here. I made two different versions, One version has a grill at the exhaust end and helps to force air on the forth side and the open exhaust version is meant to fit in tighter areas where the exhaust has to fit against a chassis piece like my NEMA does that moves the bed. I found even the open end still cools the forth side fairly well. MAKE SURE to mirror the image correctly in your slicer program to fit the motor plug location! These coolers use standard 40mm fans and 3mm wide screws should simply thread into the cooler without any issues. I did include a space for the screw head on the inside of the cooling shell if you wish to fit the fan screws from the inside out then use nuts on the out side of the fan, but just screwing them in from the fan end works really well. I am glad to say after installing these my stepper motors don't even get warm after many hours of continuous printing! If you print this, please upload a pic to the "I Made One" tab. I love seeing my designs get printed :) Thanks!