I wanted a diffuser for my Thrunite T1. They are super handy to convert you flashlight onto a lantern that can light up a room in a power outage.
I made 2 versions: one that is a closed cap and one that has a thru-hole so that it can still be used as a flashlight. I printed one in white to use as a lantern and one in red to use in a roadside emergency and not blind other drivers.
Print solid with 4 perimeters. Doesn't need supports or brims (unless your bed adhesion is not so great).