This is a picture frame for a normal 4x6 picture (normal in the US) with two parts that slide together with your picture in the middle. Comes in both a horizontal and vertical orientation.

Simply print the front and back parts. The back piece then slides into the front piece with your picture in between. This is a good test of how level your print bed is, as an unlevel bed can cause curling in the corners. This was printed on an Ultimaker with 15% infill at 0.2 mm layer height.

The kickstand on the back part works right off the print bed with very little effort. The OpenSCAD files are coming after I clean them up a bit.