Case: finish enclosure for v4

[nglgzz]

Things I'm missing for the enclosure:

• Share Fusion 360 project (available here)
• Figure out if it's better to have an extra component for the connector, or if it should be part of one of the halves (currently it's an extra component).
• Add bottom lid
• Add holes for M3 screws
• Add screws to list of materials (and heat set inserts)
• Add STL models of all components
• Update case/README.md

Early render:

[nglgzz]

Having one of the halves be the connector makes for a sturdier assembly, a cleaner look, and makes it easier to switch between split/one-piece modes.

3D printing the new model requires more careful cleanup, as some of the supports are slightly awkward to reach, but nothing too difficult.

Updated render:

[nglgzz]

The case is almost finished. Waiting on the set inserts and new magnets to finalize the design.