Summary

MosFet relay for heated bed.
Includes both source and *.stl files
Mounts to 20x20 extrusion and possibly others.
Has space for 40mm x 40mm fan on top.
This is a heavy duty box. Most are 5mm thick.
Top is 2mm thick.

I edited the MosFet_Mounted_Board file. I found that the M5 mounting holes were a little tight so I enlarged them.

I like using captive nuts when ever possible.
This box uses 12 M3 nuts.
12 M3 X 10mm mounting screws.
2 M5 X 10mm screws
2 M5 T-nuts for 20X20 Aluminum extrusion mounting.