I designed this frame for my mirror panel I had lying around. The design itself is pretty minimalistic, but you could make it more colourful and exciting if you like :)
I found that the dimensions is universal and can be bought in most hardware stores.
As shown on the photos; the assembly is foolproof. Just remove the support and press all four edges in place, they will not fall out.
If you print this, please post a picture in the comments. I would love to see what colour combinations you use! :)
I hope this is useful for you. Also, please leave a comment if you have any questions/comments.
I used automatic generated (PrusaSlicer) to cover the gap
0.25mm layer height