
Here’s an HDD synth project for that very thing I saw the other day! Though probably won’t work for your use case, admittedly. It’s intended for retro systems and goes in an ISA slot, and isn’t available for sale yet anyway.
YouTube video: https://m.youtube.com/watch?v=sASOfpzPjxg
Project page: https://www.strifestreams.com/hddsynth



I’m accustomed to the imperial system. But agree that metric is better.
Some metric stuff I have no trouble with. I have a good spatial sense of the distance of a mm, m, and km. And can do a rough miles to km (and vice versa) conversion in my head. I have a good sense of how much a kg is and similarly can do a rough conversion to and from lbs in my head. But while I understand that a gram is 1/1000 of a kg, if handed a small object and asked to guess how many grams it is, I’d fail miserably.
Celsius I can’t ever remember the conversion, but I’ve had enough exposure to it that I understand if it means cold/cool/warm/hot weather.