The front face and outer walls/frame are meant be printed in as one piece, face down. The back panel is separate and can be glued into place.

The back panel also has holes for a rocker switch and panel mount power jack. I wanted a clean box with no holes in it or cords running out of it.

I stuck the light strip to the outer frame/walls and put some aluminum/metallic tape on the back wall to help reflect the light evenly.

This did require minimal soldering to attach the wires to the power jack & rocker switch.

Parts List:
Power Supply
R-Tech12V 1A Power Supply, Power Adapters, Lighting Low Voltage Transformers 5 Pack, UL-Listed, Power Cord with 5.5x2.1mm Tips, AC 100-240V to DC 12V 1A for LED Strip Light, Camera, Router, etc. https://a.co/d/cCdednv

Power Jack
Antrader 24pcs 5.5mm x 2.1mm 2 Pin DC Power Female Panel Mount Jack Socket Connector https://a.co/d/jgyBCKy

Light Strip (trim to size)
TUNICHX COB LED Strip Light DC 12V LED Strip Light Flexible Super Bright LED Strips,16.4ft 4000K Natural White,CRI 90+,2400LEDs High Density Uniform Light for Home Decor(No Adapter or Controller) https://a.co/d/bfHYi6N

Connectors & Wire
HOMELYLIFE 2Pin COB LED Strip Connectors 8mm Soldless 10 Pack with 16.4ft Extension Cable for 8mm Width COB LED Strip Lights https://a.co/d/gFQxcUc

Rocker Switch
Round Rocker Switch, 6 Pcs Mini Rocker Switch, 12 Volt ON Off Toggle Switch with Pre-Wired 6A/250V 10A/125V AC, 12VDC Electrical Switches for Boat, Car etc, KCD1-X-Y https://a.co/d/39DWH3T