This is a case for the RasPi v1-3, a dual USB Step Down module which incorporates the Ender 3 Pro PSU. It comes in two halves not just for ease of printing and assembly, but for ease of access to the RasPi if needed. This design, also incorporates cable tidy. So you can hide the power cable for the RasPi, inside the case.
There is no need for an external cooling fan for the RasPi, as the internal PSU fan is directly behind the RasPi and it will cool it down, when it operates. i have ran 30+hr prints with no overheating issues at all.
I have designed this, to have as little amount of extras as possible.
RasPi - I used an old RasPi model 2, but the RasPi model 3 will work.
Step Down - This is a Dual USB 9V/12V/24V/36V to 5V Converter DC-DC 3A Step Down Power Module that i purchased on Amazon - HERE
x4 Screws (to secure RasPi) - 1/4inch self tappers. I had similar to these from a different project - HERE
x2 150mm (6 inches) 16-14awg Electrical Wire - For this, i used some blue and brown cable form an extension cord that was spare.
x1 M4 x 8 - HERE
Remove the power supply and PSU from the printer.
1. Remove the original PSU cover from the PSU, keeping the x3 M4x8 bolts safe for later.
2. ***IMPORTANT*** Take note, which cable from the power supply goes to which connection on the PSU. Disconnect the power connector from the PSU.
3. Remove the power connector from the cover. keep the 2 screws safe, as they will be used later.
1. Insert the Dual USB Step Down into the clips and press in.
2. Connect the Dual USB Step Down to the PSU. ***IMPORTANT*** you must connect the correct terminals on the Step Down to the PSU. they will be marked on the Step Down board and on the PSU.
3. Fit the power supply switch to the case using the original screws. Connect the power supply to the PSU. ***IMPORTANT*** Make sure that you reconnect the cables to the correct terminals on the PSU.
4. Slide lower case onto the PSU and secure it with x2 M4x8 bolts that you removed from the original case. I put one on the side (next to the USB) and one on the back, closest to the printers pillar. I left the the other empty. ***OPTIONAL*** purchase/use a spare m4x8 bolt for the other securing hole. Mine fits ok without.
1. At a 45 degree angle, insert the RasPi USB connection into the slot first, then rotate the RasPi so that the USB and Ethernet connections fit into the slot. Now push the RasPi up to the top of the case, for the power HDMI and audio connections to be flush with the case and the 4 securing holes line up.
2. Screw down the RasPi using x4 1/4inch self tapping screws.
3. Connect the USB power cable to the power connector of the RasPi and run the cable through the slot at the top, through the inner wall and coil it up if necessary and have some cable coming out at the side, next to the USB cut out.
4. Place the top section onto the bottom section, using the 3 lugs.
5. Secure the top half using the remaining original M4x8 bolt.
6. Refit the PSU to the printer. Connect the RasPi USB cable to the Step Down USB.
7. Connect the main power supply and turn on. Both the printer and RasPi should both power up.