Remixed the photo frame to integrate it with backlit LED(s);
Depending on how you want it back-lit, you can use a single LED (center) or two (left/right). It should all friction fit although PLA required some sanding. Prints without support. You can glue the LED bridge to the frame if needed to keep the arms from expanding out.
To use two LEDs:
Option 1 - put the two LEDs on the LED bridge, to the left and right of the battery making sure your polarity is correct and insert cap apply enough pressure turn it on.
Option 2 - insert LEDs into side bar then interweave into CR2025/CR2032 battery and insert cap to turn it on. This way you could slide the LED bridge out to turn it off or swap out LEDs colors a little easier.
The LED leads I use are long enough so I don't need to solder any wires unless you put the LEDs on the furthest part of the side bar. Single battery should last up to 2-3 weeks - orange and red LEDs should use a resistor; this is intended for an always on gallery/showcase installation - designing a real switch element would be ideal however that would probably require you to do some soldering and/or some redesign of the base/cap to avoid soldering although could include a mini-breadboard on the back side if it didn't weigh it all down too much...