Been into computer hardware for not very long and got dragged into the Small Form Factor PC space immediately.
The pinnacle for me for a while what getting recent hardware into a PC case as small as a shoebox
I've started with PCs as small as 20L and now have my PC in a case less that 10L. The urge to go smaller while maintaining the same amount of power is hard to resist.
There are others doing full custom watercooling loops in PCs smaller than mine but that is a whole other rabbit hole i don't think i am ready for.