Skulls! - a lithophane. It has a layer or two of grey and black inside to mask the background and bring out some details.

This has been sized to work with the light board that Bambulab sells - but I havent printed out a frame yet to piece it together.

Print at 100% infill with a layer height of 0.08mm with a base layer of 0.2mm

Filaments Used:
PLA BambuLab Basic Jade White Transmission Distance: 5
PLA Paramount 3D Prototype Gray Transmission Distance: 3
PLA BambuLab Basic Jade White Transmission Distance: 5
PLA Generic Black Transmission Distance: 0.2
PLA BambuLab Basic Jade White Transmission Distance: 5

Swap Instructions:
Start with White
At layer #16 (1.4mm) swap to Light Gray
At layer #18 (1.56mm) swap to White
At layer #26 (2.2mm) swap to Black
At layer #27 (2.28mm) swap to White for the rest.