I'm getting back to finally sorting out the recreated FD42 extension board. Mr Robot on the AtariAge forums kindly created the PCB layout for me. Thanks also to Charles/Gammaray for the correct dimensions of the expansion port BUS. I took Marks advice to go with header pins for the vertical connector. I've attached the 3d renders of the proposed PCB which are currently missing the tracks as I was confirming the dimensions inside the case with paper templates. The renders show the header pins in place on the break off vertical connector but they will of course be right angled pins installed there.
Would it be possible to make up a two way connector to attach the extension to the 81 board without soldering? The extension PCB will have all double sided edge connectors.
You can also buy from eBay, but will have to cut it to size yourself.
https://www.ebay.co.uk/itm/Sinclair-ZX- ... 0906239646
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube