I needed a simple custom shaped ‘jiffy box’ style enclosure. So I made a parametric model.

Overall dimensions as well as thickness can be adjusted. Corner radius has a small amount of adjustment.

Design is for M3 button head screws.

Theres a sealing lip with adjustable fit to locate the lid in place and provide some dust resistance. The chamfer can be adjusted for a looser / tighter fit For a small box 0.2mm seems to work well. Larger boxes might need this increased. Recommend no more than Thickness/4.

It was done in Fusion360. I hope it is useful to someone else!

I‘ll probably generate some STEP files of different dimensions when I get a chance. Drop me a line if you’d like one but don’t have access to fusion.