My case is made form 6 panels, but the top and the front open. These are held in place using magnets. That means two sides, the base, and the back need to be stuck together. At the back/bottom 3 sides meet, and at the back/top and front/bottom two pieces meet. I there printed two different pieces to connect these panels:

The blocks on the left has 3 clean sides which are glued to the three pieces of acrylic which meet at the lower back corners. The blocks on the right have two clean faces and a single indent into which a magnet is glued. This secures the two pieces of acrylic which meet at the front/bottom and back/top leading the magnet side to later secure an extra, removable pieces of acrylic, which will also have magnets attached.

Fine final kind of corner has a single clean side and two magnet holes. These are mounted on the single acrylic panel at the front/top which the two magnets used to secure the detachable front and detachable top.