Inspired by mikelb0013's design on Makerworld, but his model had very tight tolerances and was only for a few different sizes that he had made. I rebuilt my own variation of it from the ground up, but inserted parameters in Fusion to allow you to set the sizes of the pictures and adjust the tolerances to your printer's specifications. The 3mf file is set to 200x200x1 pictures with a 0.2mm tolerance as I needed those dimensions for another project. The ones in the image are 100x100x2.5 with a 0.1mm tolerance.

There are 5 adjustable parameters in this design:

Picture Height
Picture Width
Picture Thickness
Frame Thickness
Tolerance

There are other parameters in the design that set minimum values for some of the parameters listed above. Please DO NOT change these, as going below these values will break parts of the model. The modifiable parameters are favorited and should appear at the top of the list.