Pi Zero Node - Friction Fit

A nice, compact Pi Zero node case! Inspired by [blankdesign's node case](https://www.thingiverse.com/thing:2841417), this case is entirely friction fit and uses the flexibility of PLA to keep components in place. The USB charging slot will need to be adjusted if you use a small TP4056, but I also included the STEP file so it should not be difficult.

Components list:
Pi Zero / Pi Zero W
18650 Li-On Cell
[SPDT Switch](https://www.amazon.com/gp/product/B007QAJST6/)
[TP4056 Li-Ion Charger](https://www.amazon.com/gp/product/B01DRT4PWY/)
[Silver Tone Metal Spring Connectors](https://www.ebay.com/itm/100pair-Silver-Tone-Metal-Spring-Battery-Contact-Plate-Set-For-AA-AAA-Batteries/202077747472)

Assembly Instructions (Note: do not add an SD card to the Pi Zero until the end!):
1. Solder all connections except the SPDT switch. This means snaking the wires through the case insert hole to hide messy wiring.
2. Gently place the Pi Zero with the connector-side first, then push against fr