Nerf Rival Nemesis Battery Cover - Fancy Ryobi Version

Remix of my previous Ryobi-powered Nemesis, this time with an added fan for getting some airflow to the PWM modules and externally-mounted controls for the PWMs for on-the-fly adjustment of fire-rate and velocity. Also includes a piece to use as a lockout for the velocity control for FPS-capped events.

Most info for the printed parts can be found at their original listings. Assembles with primarily socket-head M3 screws and M3 heatset inserts, I mostly just used what fit best out of an M3 screw assortment.

Hardware used:

• Fan: https://www.amazon.com/Noctua-NF-A4x20-FLX-Premium-40x20mm/dp/B072JK9GX6/ The fixed 12v version is used for ease of use, other versions would need more components to control the speed. Other 40mm fans should work, but I haven't confirmed it.
• Pushbutton: https://www.amazon.com/gp/product/B07D7S1NXY/ This is an on-off for the fan just as an option. Needs to be a latching/toggle type to stay on when pressed. 
• Buck module: https://www.amazon.com/gp/product/B01MQGMOKI/ Needs to be able to handle ~20V input, doesn't need much current as it's just for the fan. 
• Main PWMs: https://www.amazon.com/gp/product/B08BNF3FZD/ Needs to fit into the battery tray, should have a wire pot for control, and should be 15A or more with fuses. 15A fusing seems fine for the stock motors at the ~20V max for this setup; I've only blown a fuse from revving after feeding, so exactly how I would want.

Parts needed from https://www.printables.com/model/424716-nerf-rival-nemesis-battery-cover-ryobi-version :

• nemesis_battery_cover-ryobi_stem.stl
• nemesis_battery_cover-ryobi_interface.stl

Recommended other parts:

• https://www.printables.com/model/519342-noctua-a40x-fan-grill 
• https://www.printables.com/model/424806-spurred-thumbnut-m4-bolt-version 
• https://www.printables.com/model/242314-ec11-rotary-encoder-knob-rotor or https://www.printables.com/model/201548-ec11-rotary-encoder-knob-spurred