BenchTopPi

What started as an attempt to build a DIY Google Home Hub, eventually became the BenchTopPi. Now instead of buying a bunch of hardware, testing, and then either not using it or finding out the hard way that it wasn't worth it, I can use this to both program Arduino boards and test out operating systems for Raspberry Pi projects. This can also be used where a small semi-portable computer may be needed.

Raspberry Pi 4B
Smarti Pi case( version 1 was used and modified to fit)
Official Raspberry Pi 7" Touchscreen
Micro SD card extender
90 degree 40 pin GPIO extender
RaspiAudio Ultra++
32 GB Micro SD card
Wireless Keyboard (preferably with trackpad, and has a usb reciever)
6" usb-c cable
6" micro usb cable
mini usb (m) to usb-c (f)
stick on cable manager
usb-c (f) split cable with usb-c (m) and micro usb (m) ends (found it on on Smarti Pi's site)
E6000 glue
small screwdriver (phillips)
Hex keys
Rotary tool (for modifying; w/ discs and various sanding ends)

When I bought this case it was several years ago before the upgrades and before the Raspberry Pi 4. On the new versions they have a more modular approach and keeps the ribbon cable inside. On the originals your supposed to use a separate case and run the ribbon cable external. I removed the lego piece on the front, drilled a hole, opened up the chassis back as needed to allow the camera module board fit and line up with the hole. Once fit correctly, I glued the module to the lego piece back (with long ribbon cable running towards the center), then glued the lego piece to the chassis. I used the lego piece designed to mount the Raspberry Pi camera on the top mount as a cover cover for the front. To add ease of removal and a little bit of "security" I glued a lego Mandalorian, with E6000 adhesive, to the lego piece.

Between the DIY Google Home Hub idea and the BenchTopPi, I got intrigued by the idea of a Raspberry Pi based mobile device. I wanted to build a Mutant-C, but I found my 3D printing abilities not yet up to that particular task. I toyed around with the idea of designing more of a regular tablet, but decided I could test all my ideas, so I decided to use what I had and build the BenchTopPi. One of the theories, I wanted to test out was using a micro SD card extender to be able to swap SD cards easily, without having to remove the Raspberry Pi every time. This gives the ability to change operating systems and tool sets, based on differing use cases. To achieve this, the best place I found was to mount it to the top, then found the best spot to run the ribbon cable, and cut a slit in the chassis to feed the ribbon cable through. I also had to remove the bar between the upper part of the chassis and the lower part of the chassis, because it interfered with the fit and fitment of the extender. Once everything was tested, fitted and modified the end of the ender was glued with E6000 adhesive. Just a note of caution : make sure when swapping micro SD cards, the Raspberry Pi is shut down. Second note of caution : in the extender end where the micro SD card fits, there is a surface mounted resistor that needs to be removed for this to work, the spot where it was located is circled in green.

The Raspberry Pi 4 is known to put off more heat, especially from the processor area and needs a fan to operate as best as can be. To accommodate the needed fan, I used a scribe to mark the size needed and then used a rotary tool and a sanding stone to open up the square to hole fit for the fan. Once I established direction of the air flow and determined where the two power leads needed to connect to the system and glued the fan to the back plate. Modification to the back plate was also needed in the upper right corner, right behind the RJ-45 (LAN) connector. This connector is larger than the USB connectors, leaving less room for the arm of the back plate. Using the rotary tool and a sanding stone, the least amount of material was removed. Additional material needed to be removed from the back plate from the stand off on the inside of the bottom left corner. The Raspberry Pi 4 has a USB-C connector for the power in, this is wider than the micro USB connector on the Raspberry Pi 3 B+. The extra width of the USB-C connector doesn't clear the stand off, so I removed the narrower upper layer. Once removed the everything fit very nicely. One more modification to the chassis had to be made to allow the dual micro HDMI connectors that stick out just a little further than the single micro HDMI connector on the Raspberry Pi 3B+. Using the rotary tool and a sanding stone i carefully removed only as much as I needed to to allow the connectors to sit down into the chassis.

One of the primary uses of this device will be to program other devices, mostly microcontroller boards, which have primarily use one of three USB based conntections, USB-C, micro USB, and mini USB. To better facilitate this, 6" cables of these types are attached using a stick on 2 lane cable manager.

In this video, https://youtu.be/coUgIC6ggBI , I go over the modifications, then go into disassembly, troubleshooting of the display ribbon cable, replacing it, then reassembling the BenchTopPi with all of the pieces, including connecting the 90 degree 40 pin GPIO extender, the RaspiAudio Ultra++, and the fan connectors (pins 2 and 3).
A few extra tips:
Plug the micro SD card extender into the Raspberry Pi 4 B before setting it in the chassis
After the micro SD card extender, go to the display connector, then the camera
Plug the keyboard USB into the bottom rear, save the USB 3.0 connectors for speed connections
The split connector ends for the screen and the Raspberry Pi 4 B without having the base attached