This cap protects the camera's fragile lens cover leaves and keeps pocket fuzz out of the lens elements inside the turret.I carry a Canon SX230HS camera in my pocket so I have a good camera with me at all times. Unfortunately, the front cover of the lens turret consists of the thinnest possible aluminum, so pressing the camera's front side against anything bends the cover against the leaves and jams them closed.This lens cap solves that problem with a sheet-metal plate that bears against the non-moving turret rim. The plastic ring spaces the plate away from the cover by two thread thicknesses, allowing the plate to absorb all the pressure without touching the lens turret.The plate recess uses a built-in support ring that you remove by twisting each small tab with a needle-nose pliers. A dab of acrylic adhesive holds the plate in place.The bright yellow filament is sufficiently hideous that I probably won't leave the cover behind. Conversely, should I turn the camera on with the cover in place, the camera shuts itself off with a lens error; this doesn't seem to do any harm.The OpenSCAD code has enough parameters that you should be able to adapt it to any camera. Even if you have a Canon SX230HS, you should regenerate the STL file to match your printer's thread dimensions to ensure a snug fit.More details on my blog: http://softsolder.com/2011/11/12/canon-sx230hs-lens-cap/