I liked the following designs but there were no covers to carry/store the MiniDiscs without them falling out of the case. Pictured are the prints for both the 5 and 10 MD Carry Case. Don't pay attention to the bed marks on the 10 MD cover. I need to flip my print bed. :) Ihae printed them and tested fitted using PLA.

The covers were based on these MD carry cases:
5 MiniDisc carry case: https://www.thingiverse.com/thing:5879657
10 Minidisc carry case: https://www.thingiverse.com/thing:5879032
by Gucabe's

Used TinkerCAD since Fusion360 (my fav) doesn't work on my Linux workstation.