Completed my second water-cooled build. Of course, not everything is perfect, but on the whole I'm satisfied. I was able to gain new experience and it was a lot of fun.
I liked the Jonsbo TK-1 straight away, as it has an unusual form factor, is nice and compact and also allows the use of mainboards with rear cabling. When I saw that it was possible to install a complete water cooling system in it, I was immediately hooked.
The components are not all high-end, as I had to watch my budget, but they are absolutely sufficient for my application.

Many thanks to all the PC builders who inspired and helped me with this build.