Box clip broke at the pin location where it rotates and others got lost. So created my own. They fit very nice and are strong.
For mounting its possible to use 4mm nail or M4 screws.
I put a little M4 screw from one side and inserted clip into its place then added another M4 screw from the side where you have more room inside the box to tighten it.
2 perimeters and 100 infill creates very strong part.