This is modified BentoBox fan case & duct allows you to use 10-32 nuts and bolts. Building BentoBox with 4028 fans requires 32mm long screws which is way easier to source with 10-32 threads.
Original BentoBox v2: https://www.printables.com/model/272525-bentobox-v20-carbon-filter-for-bambu-lab-x1c-enclo
Requires 4x 10-32 hex nuts, and 4x 10-32 screws that fits your installation. The nuts MUST measure 9.45mm wide (measure between 2 opposite hex flat faces), and 3.2mm tall. A tolerance of 0.2mm is built into the models.
Printing instructions:
Step 1: Getting the settings in your slicer.
I prepared a 3mf file with all printing settings tweaked and tested so you can save some time. This file is tuned to use ABS, the most important settings are 1) the infill density modifier cube and 2) pause at layer for adding nuts.
[Continue to setp2 if you're using supplied 3mf file] If you ever choose to slice these models yourself, I recommend using the original 3mf file from BentoBox as a starting point, then use "Replace with STL" to replace fan case & duct models with the ones here. Then, you need to add a pause on the first layer after hex nuts slots; Then, add a modifier to print 100% infill density around the hex nuts. I recommend print with 100% infill starting 2mm below the nuts, all the will until 2mm above the nuts. This might be an overkill for BentoBox but is the correct thing to do whenever you're using embedding hex nuts in your 3d prints. I'd not want to test my luck on this one.
Step 2: Install nuts Once the print paused, insert the nuts in the hex slots in the models. If you're printing with ABS, allow the nuts to get to chamber temperature before resume printing, by simply wait about 5-10 minutes.
Step 3: Post processing 1 layer of filament is printed above the nuts to avoid printing holes floating in the air. You need to tear that layer away before installing screws. You can use any tools for this but I found it's easier with a wood screw.