A friend is trying find the original brand and model of this old 1990’s generic case. An ad from computershopper would help.
I doubt there is any Brand or Model to be found, as this is a middle of the road no name case, produced by some Asian, most likely Taiwanese, company, sold in bulk as commodity. These companies did never intend to build a brand at all as this would have worked against their sales.
Even more so, these case manufacturers were often themself relying on random suppliers, so the look was defined by what front plates they could buy from a front plate manufacturer. Various manufacturers were supplied by the same front plate company. It was a pure capitalist world of copying. And competition meant as well that front plate companies copied moulds from each other.
If it's about finding the 'right' sticker that was on there, it's even more random. It could have been from the box manufacturer (unlikely, the shop configuring the PC (larger ones did do their own), the mainboard manufacturer - during the 90s and early naughties Mainboard manufacturers delivered stickers with their products - or CPU manufacturers who did alike. Many ways one could show off.
Bottom line: Without having any explicite trace, it's impossible to give a hint for either - even finding similar cases won't do it.
Here's a discussion on Vogons from a person called Firage with the same case. You might be able to get in touch with them via that site and ask.