To not annoy my collegues in the office too much with keyboard noise I don't use my IBM Model M at work.
Some time ago I modified a left over MS Sculpt ergonomic keyboard. Originally it's wireless but with some proprietary USB wireless dongle. I got this keyboard because the person is still using the Sculpt mouse and needs the dongle for it but has no use for the keyboard and buying another dongle is impossible.
So I checked if someone already modded a MS Sculpt before and voilà I had a neat little modification project.
The modification basically follows the wired sculpt mod from Chad Austin.
I still had a Teensy++ 2.0 lying around from another project I never started in the end. So instead of ordering the PCB made by Chad I went for a hand-wiring modification (Like he did for prototyping) and I only had to order a FP30 1mm pitch break out board. If you use thin wires and carefully route them from the adapter to the Teensy it's possible to squeeze it in (Some plastic need to be removed with a Dremel or so to make space for the Teensy).
To be able to drive both LEDs and read out the layer selection switch Chad added a complicated circuit with a charge pump to generate negative supply voltage. This is unneeded complicated and I changed that part of the schematic. It's documented in my Rev5 board design proposal.
I wired the bootloader button from the Teensy board to the pins of the Sculpt battery compartment. This way you can enter the Teensy bootloader simply by connecting the two otherwise unused battery pins. No additional buttons or holes in the case needed.
Schematic wired-sculpt.pdf
Modified QMK firmware for the rev5 Sculpt mod wired-sculpt-pcb-master.zip or on Github.