Framing pictures is a pain, especially when the frame is too thin or the picture is too thick and you just can't find the right size of clips at the hobby store.
Oh, wait. I can make anything I want, any size I want.
One might rightly question if these are as sturdy as the metal clips. After all, even with 100% infill and vapor smoothed surely these can't last last long as the metal clips? Maybe not. But being plastic they'll probably outlast the frame. And they seem to be holding so far.