Summary
I wanted to add some fans to the front of my K40 for smoke assist. I designed two things (a drilling template and a fan cover) using Tinkercad and Inkscape. Both were remixed from fan covers found on Thingiverse. Cut the drilling template and tape it to the outside of the K40 case. It will probably be destroyed while drilling the holes but that is ok. After the holes are cut use a file to take the burrs off the edge. After cutting the fan cover out of acrylic just spray the back of it black and it will look nice.
The fans only took about two weeks to be delivered from China to South Carolina, USA.
FWIW, I am using these fans in conjunction with the stock exhaust fan that is supplied with the K40.
I used:
4 x 4020 fans from AliExpress (buy extras in case the cheap fans are broken)
38mm hole saw
3mm screws, washers, nuts I had sitting in a box
Some scrap acrylic from an old arcade machine.
Satin black paint
