UPDATE: I noticed several artifacts in the final print that didn't reveal themselves when rendering in OpenSCAD or slicing in Cura. I think it's from cutting and chopping up the donor stl in OpenSCAD so I rewrote it from scratch in OpenSCAD and uploaded it as Version 2.0. It is as faithful to the original as I could make except I made the walls thicker and didn't hollow out the inside of the ends. All that combined to make it much stronger and not as brittle and fragile.
I remixed tekblub's cr-10 control box base plate & legs for dual 120mm fans but replaced the honeycomb hole pattern with a clean 117mm hole for my Noctua fans I removed the honeycomb pattern to help the fans run as quiet and efficient as possible but also to save a little filament. I used tiny washers for the 3mm screws that attach it to the case. I didn't print the legs but instead screwed on 17mm wide by 13mm tall rubber feet using the fan mounting screws. I originally planned to use adhesive rubber feet but I couldn't keep the narrow fan screw heads from going all the way through the PLA holes without a washer and the adhesive feet wouldn't stick with the screw heads and washers sticking out. The base is extremely fragile coming off the printer because of the thin walls and floor. I didn't even use a scraper for fear of cracking it; I slipped dental floss underneath it and used a sawing motion to separate it from the bed. Once you install those big fans, though, their thick nylon frames give it all the strength and support it needs. I was able to print it on a CR-10, obviously, but I had to increase the print bed size to 307mm x 307mm in the machine settings in Cura just to get it to accept the stl and export the gcode.
May need to set bed size slightly larger than 300mm x 300mm in slicer to print on a CR-10.