zlacker

>>susam+(OP)
This has inspired me to try to make my own custom keyboard. Does anyone know of a good keyboard remapping tool for the Mac? I have BetterTouchTool, but I've found it's not reliable on my machine. (And probably other people's machines, which is why it includes a "Restart" option in its menu.)

I like the keyboard company the article links to, but the keyboards it offers don't have the full range of function keys that macOS supports (It's four short). Are there other custom-printed keyboard companies I should consider?

>>reaper+3V
If you want to do something like the article, with a custom layout (e.g. defining characters for Option and Shift+Option), then what you want (as hyperjeff mentioned above) is Ukelele https://software.sil.org/ukelele/