It has 2 versions, one with a slot for customizable plates and one without. The dimensions of the customizable plates are 42x10x1mm. You can make signs in these dimensions yourself, if you have no experience there are many tutorials, e.g. Tinkercad .

Dimensions:
The frame is designed for a size of 52x86mm, if you want it bigger or smaller you can use the following calculation:
Width: Desired width / 52 * 100 = (This is the multiplier)
Length: Desired length / 86 * 100 = (This is then the multiplier)
You can then enlarge it in the slicer with this value. Remember to enlarge everything and not just the frame.

Print Settings:
I printed everything with a layer height of 0.2mm, all files need support. The objects are printed with the visible top side facing down! (Except points.)