In my city you can’t diy electric without a license if you intend to sell soon. It’s a reasonable precaution to prevent shoddy flips. I assume plumbing works the same way. Just installing a toilet might be fine though, it’s pretty straightforward.
I built a 4x5 dactyl manuform and use it for coding. I will definitely be going with a bigger layout for whatever I do next. The really small layouts are amazing for prose, but for code that makes heavy use of unusual punctuation, it’s not ideal. Layers are great and I really prefer having numbers on a layer, for example, but then for something like typing a version number I have to switch layers every other character. It would be great to have enough keys to have things like period and colon available on multiple layers.