Ender 3 BTT U2C v2.1 Enclosure/Mount

Designed to “work” with my MKS Pi mount. Well that isn't to say that it won't work without it, but I have designed it to sit flush with the stock electronics enclosure aluminum cover when the aforementioned Pi mount is in place, which essentially acts a 6 mm spacer.

Bill of Materials (BOM):

• M3 Heat-Set Threaded Inserts (OD: 4 mm/L: 5.3 mm): 9 pcs
• M3 x 6 mm Bolts: 12 pcs
• M3 x 12 Bolts: 3 pcs
• M3 T-Nuts/Hammer Nuts: 6 pcs (https://www.aliexpress.com/item/32814359094.html)

Note: The Z-axis stepper motor cable is a bit too short to route through the enclosure to the Z- axis motor. Since I have converted my printer to use an Orbiter 2.0, I had a spare stepper motor cable lying around from the stock extruder, so I just used that instead. I assume anyone attempting this will already have converted to some form of DD system, so you should have this cable lying around as well.

Assembly's pretty straightforward:

• Print all parts in the filament of your choice (I used black PETG).
• Insert all nine M3 threaded inserts with the aid of your soldering iron.
• Assemble the 2 top cover pieces (the smaller “Cap 2” part could be considered optional - I made it a separate part from the main top cover to optimize its strength. You can completely omit it if you don't mind a bigger hole in the back I suppose).
• Before trying to install the box on the printer, insert all M3 x 6 mm bolts used to secure the box on the aluminum extrusions and screw - just barely - a M3 T-nut on each bolt. This will make attaching the enclosure to the printer much easier.
• Lift your printer up a bit and slide the box from the rear to the front. Make sure they actually slide where they're supposed to go.
• Once in place, tighten one of the screws to secure the box in place. Next, with the box somewhat secure, completely unscrew a bolt from its respective T-nut, then fully tighten. This will ensure that the T-nut will rotate 90 degrees and will actually anchor on the aluminum extrusion.
• Repeat the last step for the rest of the bolts. A flexible attachment for your screwdriver will prove very useful as its a bit hard to access some of the bolts.
• Mount the U2C board on the top cover using 4 M3 x 6 mm bolts. Connect the USB cable on the Type C port on the board.
• Place the top cover on the box, after routing your printer's cables, then secure it with 3 M3 x 12 mm bolts.

Yes I haven't finished setting up CANbus yet, but I've tested everything and there's nothing interfering with anything as far as I can tell. I should also mention that the box is “missing” a corner so as to not interfere with the brackets I used (https://www.aliexpress.com/item/32870543302.html) to stiffen the printer's frame.

To wire everything up, I used 2 x 5 terminal WAGO-style connectors, one for positive, one for ground. You can find such connectors in your local electrical supplies store.

As for the USB cable, I used this 90 degree USB Type A to Type C cable: 

https://www.aliexpress.com/item/1005001626467639.html 

to connect the U2C board to my MKS Pi. It's a bit longer than what would be considered optimal (the cable's 50 cm long but 40 cm would be better - but such cable is impossible to find, so we'll just have to live with it).

Finally, a recommendation to the one other person who's looking into converting their stock Ender 3 to Klipper + adding stuff like CANbus, etc. Perhaps look into the MANTAE3EZ mainboard before going into this rabbit hole. It will cost a bit more, but arguably saves a lot of time and will be somewhat more integrated. Unfortunately I already had the SKR Mini E3 v3 + the Pi installed on my printer when this came out, so I'm stuck with what you're seeing (although feature wise, you're getting everything but the 5th stepper driver slot + access to high voltage drivers).