Summary

A cap to protect people against the sharp edges of a three-sided aluminium profile measuring roughly 20.2mm on the short sides, 40.15mm on the long, and 3.15mm thick.

I made this for a friend and forgot to take picture of it before giving it away, hence the screenshot (but it has been printed successfully), so please post yours if you make one.

Sketchup source included if you need another size.