DIY

Look fab labs, hacker space, maker spaces or whatever it is named in your area. Those are not exactly everywhere, but common enough to have a look at. Another somewhat related space would be a repair cafe. That would give you not only access to a workshop, but also a bunch of folks for inspiration.

Other then that look up Arduino and RaspberryPi solar projects. It is pretty easy to find some lists. 3d printers are pretty common, as are many other similar tools. Home automation can also be interesting, but that might not be that great of an option, if you rent. Micromobility can also be somewhat interesting(elector skateboards, self assembling a bicycle....). It is also rather easy to set up a solar system in a flat, as long as you can easily install it outside it on a balcony or whatever. There is also a pretty large diy loudpspeaker community, which apparently is pretty easy to built.

Honestly there are lots of projects. Just think of something you would like to have and look up diy version of it. Seriously people built nearly everything at home. There even was a supersonic kit plane sold once, which apparently never managed to go supersonic and had a habit of killing its pilots, but you get my point.