I've got a few C= machines lying around. It's more for nostalgia than anything, I rarely use them.
I have a 1080 Amiga monitor, a SX-64 (with keyboard cable), a 1571 drive, a 1581, a boosted 1764 512k RAM expansion, a Super Snapshot, the 1351 mouse... A home-made power supply since the original brick is unreliable, runs too hot.
Bunch of other weird stuff like the SFD-1001 drive, IEEE interface and a stringy floppy drive.
When I used GEOS 2.0 on the C64 with the RAM, mouse and 1581 it was a surprisingly capable system 20 or so years ago.
I built my 128DCR from 3 dead motherboards I found on eBay, the case and keyboard from "as is" auctions. It still has a few holes drilled in the front panel from the previous owner. It's quite a mutt!
Years ago I tried my hand in designing a RGBI to VGA converter which was more difficult than I thought. I got it to convert but I never got the colors to work correctly. Even after going through all the registers of the converter chip all I ever got out of it was purple and green.
I also had clock problems, I was aiming for pixel-perfect upscaling at any horizontal resolution and I was unable to design a clock recovery circuit to do so.