I redid the side panel for the CoreOne L for use with @TheNexusAvenger "BentoRoll" Recirculation Filter and added a built in switch box for external control. STL and STEP files attached. 

Switch I used and the barrel connector for power I used are listed below. 

https://www.amazon.com/dp/B0CJQ9HX74  24vdc switch

https://www.amazon.com/dp/B08SJM2G52 Barrel Connectors 

You will also need a few M3 heatsinks for the back cover. 

I printed everything in Elegoo PETG-GF.