Does it need one?
The tape could just be hand placed on spindles on an open deck, a bit like at 0.28 in this video:
https://www.youtube.com/watch?v=gG4Jt-VxMpg
Granted this guy had taken the spools out of the cassette, but this is what I was thinking when I say 'bare bones'. A clear perspex lid could go over it like a record deck to keep dust out.