Pi Zero 2 W Palmtop

This project is a remix of the tagged "Mini Raspberry Pi Handheld Notebook" Project with a few particular goals in mind

• Compatibility with the 2.8" Adafruit SKU 2298 screen - I had one of these on hand, and I don't like having spare parts floating about
• Rigidity - the original design (at least for me) needed a bit more strength; this is a design I intend to eventually iterate on but this is a basis where I wanted to begin with something that feels solid and usable. Also more material around screw/anchor points for repeat assembly and disassembly.
• Simplicity - I wasn't a huge fan of the original designs' method of sending the battery between the pi and the screen, nor anything involving bending GPIO pins
• Size - The original design incorporates one of the larger format Pi models, and I wanted to try (and did) shave off some of the vertical height; roughly a third. I'm a big fan of Palmtops, and when this one goes to valhalla I will iterate and go thinner, again, probably with a bigger screen.

Based on those goals there's some compromises you should know about before going straight to the printer:

• It's designed around a Pi Zero 2 W - it's not a weapon, and I ended up running Pi OS Lite and using browsers like Links2 which also lends itself to the small resolution
• It's designed around a small screen - this did, however, allow for things like being able to just double-sided-tape the battery onto the inner face of the case. No rattles.
• It's designed around an 1100mAh battery which allowed it to sit aside from the Pi and screen, directly under where the power switch is located. You'll get hours at low intensity, or less than an hour if you'd like to try and have it melt in your hands.
• It foregoes the speaker of the original design. Getting the gear in for the speaker and amp wasn't something I was willing to go for in this iteration.

Parts used were as follows:

• Pi Zero 2 W
• ADA1988 ribbon cable (which you'll need to cut down to a shorter length)
• ADA2465 - The Adafruit Powerboost 1000c
• ADA2298 - The Afafruit "PiTFT Plus Assembled 320x240 2.8" TFT + Resistive Touchscreen" - which was the basis of this build.
• The Rii Mini X1 Keyboard - found at http://www.riitek.com/product/218.html - and through various retailers
• A lithium polymer battery, 3.7v, at whatever capacity you're willing to have potentially send you sterile if it goes wrong. I used an 1100mAh battery found here: https://core-electronics.com.au/polymer-lithium-ion-battery-1000mah-38458.html
• A slide switch to handle power toggling - Adafruit have https://www.adafruit.com/product/805, but you may find others about.
• A USB OTG Host cable - such as this one: https://littlebirdelectronics.com.au/products/usb-otg-host-cable-microb-otg-male-to-a-female?_pos=4&_sid=5877f6ff7&_ss=r - which you'll need to adapt the Pi Zero 2's OTG port to the USB-A that the Rii Mini X1 uses.
• A right-angle USB OTG Adaptor so you can actually get at the ports of the upside-down-pi, IF the above cable doesn't already have a right angle on the micro usb side.
• Leftover ribbon cable OR other cable of appropriate gauge to run ~5v; I just yanked a black and red length or two off my butchered ribbon cable to mark power and ground, and hit them with the wire strippers.

On Printing:

• I used a pretty much bone stock Ender 3 V2, with Prusaslicer - Cura was slower, and had troubles with some of the supports. Or more likely, the Ender 3 had trouble. Either way: 100% infill because you don't want this thing going bang, and Ironing everywhere you can throw it to get those thin case edges fully enclosed and tidy. I used PLA+ filament from 3D Fillies, nothing fancy.

On construction:

• Rather than attach the Pi directly to the header block on the screen, I used the ribbon cable on the set of GPIO pins directly behind the block, and ran it to the pi on the other end. This allowed me to reduce the thickness by what would have been the pi stacked directly on top of the GPIO header block.
• You'll need Glue for the hinges to get them on the case - they're keyed to fit the case, courtesy of the original creators. You'll also need to glue the switch in - carefully - you wouldn't want to get glue in the switch.
  Once the screen, cable, and Pi are affixed (which will require you cutting the cable down to length and pressing the header back on - use a vice if you can, carefully), you then can solder the switch to the powerboost, and then to the back of the pi. The connections you'll be making can be found here: https://learn.adafruit.com/pigrrl-zero/power - just keep in mind that tutorial covers more than the total of 4 connections we're soldering here, so don't stress when you open it up.
• Recommend taping the battery to the inside of the case to keep it from rattling about, along with any other accessories you throw in.