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oh I see, the rounded silver thing is a touchpad? I have at least one old laptop touchpad laying around, maybe i'll see if I can get it to work with a PS2 to USB adapter. I also might just order the blackberry trackball and some arduino-like tiny dev board and try to write the software myself. my case and screen are coming on august 26th, and I am going to start out with a Pi 2 as the computer until I can get a better one, since right now my Pi 3 is hosting HomeAssistant for me.
Happy to see other great builds here, thank you for sharing! I've also published a status update on the original build, hope you might find something useful.
Thanks for sharing this cool laptop !
I also built my own:
More info on my website.
In the project pictured above I re-purposed an old laptop touchpad. You can find many trackpad pinouts of them online and then use a PS/2 to USB converter (which is hidden under the keyboard) to connect it to USB.
If you want a ready-to go solution, I can also recommend the ergonomictouchpad.com touchpads. Expensive, but many sizes available and works very well, even has support for gestures and right-click, which is also nice. I had one of them but sadly destroyed it while trying to shorten the cable, still not sure what went wrong exactly.
You can also look at finger or pen mouse options, but I have no experience with them.