Is a generic old 486 case. Have a very similar one and no way to figure out who made it (not that it matters).

Guesses go along the lines of probably Taiwanese, probably at least 3 manufactuers that were virtual clones of each other, probably appeared just a bit before 486es because there were late 286es and 386es found in them. May have been used through socket 5 Pentium by some system builders. Best guess for finding one, determine who local/regional system builders were in the late 80s through 1990s, who used the case (Library, newspapers and magazine ads) and camp on all the computer sections of every local classified for a 100 mile radius around you until one gets a mention.

That's a generic, mass-manufactured PC case. Definitely not something that was customized for anyone, but it was most certainly something sold in bulk orders to countless PC builder shops and mail-order assembly resellers, who would fill it up with whatever components a customer ordered or they chose to offer in their catalogues.

Here's a couple in retired, un-restored state. Right side of pic, they're both actually same height, pic distorted them a bit. One you can see has the switch high, but no turbo display cutout in the fascia vinyl(?) but there may be one in the case front plastic behind. The other has turbo display, but the switch in that panel and the badge spot high. Neither of them have any identification markings at all.