I wanted to place this filament dryer I got myself recently directly above my printer. So I designed and printed this shelf. It prints in parts to get as strong as possible and can be assembled using M3 screws. If you are interested, files are available here for free:
https://www.printables.com/de/model/539326-esun-trockenbox-wandhalter-esun-filament-dryer-wal
Hmm… I doubt that such a device would sell well :D