For length, for an average male one meter is about one large step with extended legs (useful for distances), or the distance between e.g. the left side of your torso to the end of the extended right hand (useful for estimating the length of rope or smth).

For weight, it might be useful that 1 liter (that’s 1 dm3 but noone uses that except sometimes in scientific literature) is almost exactly 1 kg, and a typical cup fits 0.25 liter. A shot of alcohol is either 20 or 40 milliliters (0.02 or 0.04 liter) depending on where you are and what you order.

For conversions you just need to remember the base unit (e.g. meter and grams/kilograms) and the decimal prefixes. But you really only need milli (1/1000), centi (1/100) and kilo (1000) in day to day life. Then you simply shift the decimal.

I just didn’t plot anything anymore tbh. I originally wanted to make stencils for electro-etching but I realized that I don’t really have that much of use for it.

I did it with my ender 3, using a printed bracket to hold the knife. It’s a hassle to use and I barely use it because it’s such a pita. I managed to make a few nice cutouts though so it’s definitely possible. I just wouldn’t recommend it.

have you tried the eurokey layout? At least for German it has all the relevant characters easily reachable.

can you not get 3rd party ones?

I don’t know what you’re trying to do but the easiest thing would be a bash script you would run after installation which does everything you want to change if it’s just some setting and packages