In the old days of computing, users often bought kits and put together their own machines. Part of the fun of owning a computer was figuring out how everything worked together. You still can build ...
A lot of open hardware projects inluding Amiga accelerator cards and C64 VIC chip replacements have come out over the last few years that are basically "slap a Raspberry Pi on a custom PCB and emulate ...
It was actually fully usable for my needs ...