This diffuser clips on to the front of your Canon MT-24EX flashheads and provides a large, evenly illuminated 175x120mm rectangular front face (~7x5 inches). The shape of the face has been chosen so that the MT-24EX's natural beam pattern completely covers it.

The focusing lamp still works but is probably no longer bright enough to be useful for anything.

Print using white PLA with 0.2mm layer height, 2 perimeters, no supports, and infill doesn't matter. Set the seam position to "random" to avoid the layer change scar lining up and causing a weakness in the wall.

The 0.2mm front face is problematic because if it is printed as a single 0.2mm layer, any underextrusion or lack of squish here will cause the diffuser face to split along the direction of the extrusion lines when pressure is applied to it.

Instead you want to print this bottom face as two 0.1mm layers. This way the second layer (which is oriented at 90 degrees) will prevent this splitting.

With PrusaSlicer 2.1 this can be achieved by setting the "first layer height" to 0.1mm, then right click the model and select "height range modifier". In the settings panel that appears, select "Start at 0.0, stop at 0.2, layer height 0.1". This will cause the bottom layer to be printed as two 0.1mm thick layers (check this on the layer view) but the rest of the model is printed in 0.2mm resolution for speed. This reduces printing time by 50% compared to just slicing the entire model at 0.1mm layer height!

The example photos were taken with this diffuser, my 300mm extension tube for Canon cameras and my Loc-Line arm system.

I've included the Fusion 360 design file so you can adapt this to your needs.