This is a quick design I made to add two 120 or140 mm fans (one on each side) to my CTC's build chamber.
Goal was to make a fan mount, which can be easily removed when you have to access the print bed from the side (i.e. to apply blue tape, capton tape).
The bottom bracket has slots so you can adjust it to different fittments (CTC doesn't have the best quality crontol).
I run all my additional fans of a PC fan-controller I build in my printer, I power it from an external 4-pin Molex PSU.
I designed to versions. One "full" version with complete brackets, and a "small" version with split bracktes (for easyier printing in ABS for less warping).
The support is importent for the "grooves" which hold the brackets on the printers frame.