I love lithophane electric night lights, but sometimes a naturally-lit one is less intrusive; just place it near a window. Here's a simple stand for curved lithophanes having a radius of around 120-150 mm and a total thickness of 2.5mm. If printed in ABS, a range of radii will work thanks to ABS' flexibility. Use one each top and bottom, or just bottom if you prefer that look.
The stand shown here was printed with PolyWood filament from Polymakr http://www.polymakr.com/ on an Afinia using the PLA profile, "Fine" speed, and 0.3mm layers.
The lithophane of my parents' wedding photo was generated using PhotoToMesh http://www.ransen.com/PhotoToMesh/ and printed in Octave natural ABS on an Afinia at "Fast" speed and 0.20mm layers.
The stand design can be edited on Tinkercad at https://tinkercad.com/things/kukqLSAmjSw. It uses the Shape Generator "Hi-Res Tube Segment" by Anthony Graglia.