Basic test bench for standard Micro ATX motherboard designed for 3D printing without supports.
It only has motherboard tray and support for 4 expansion cards. No I/O shield or anything else, has cut-out on the back for easier cooler and back SSD access (if any).
I was printing it with 1mm nozzle, 0.5m layer height and 30% infill in PLA on Creality CR-5 Pro H.
Motherboard can be secured with M3 screws and expansion cards with 6-32 screws like most standard cases. They will tap right in, no need for inserts or anything.
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