... I had the unexpected privilege of meeting a gentlemen, who (over twenty years ago, and with a team of mates) built what I can only describe as a "clone" of the BBC Micro (actually he/they made forty of them). The surviving example lives in his garden shed, and (at first glance) could be mistaken for an Acorn Atom (the predecessor to the BBC Micro that had so impressed the BBC Computer Literacy Project people). That was because the function keys were grey, rather than the familiar red. But upon closer inspection, I could see that the BBC-like casing was made of fibre-glass. And then, when the lid was lifted ... guess what? The board inside was definitely "home grown". It was nothing like the usual Beeb. Brilliant!
Just in case there were any doubters (?) ... see this
In similar vein, I can't remember if I've linked to this one before, but you'll find some very "interesting" kit shown here