Normally when I make a Commodore plus/4 USB keyboard, I start with one that has a broken flat flex, and replace that with a pin header and plug on the USB keyboard controller.
I've been asked for a Commodore plus/4 USB keyboard kit, so here is a version that can be used on a plus/4 that has a working keyboard and an intact flat flex (and most likely a faulty TED or 8501).
This version has a fixed keyboard mapping, so all the keys mapped appropriately for the normal desktop use. I do a version with a mode switch for emulator use, but that requires a bit more modification and changing the LED etc., so that is not available as a kit.
You can order a complete Commodore plus/4 USB keyboard from my Etsy store, or the conversion kit below.
Tune in tomorrow to open another window on the Advent Calendar of USB keyboards.