Flickr user RawSniper1 creates a lens cap holder using nothing but a couple of Lego pieces. A thin eight-stud piece permanently glued to the front of the lens cap easily attaches and detaches from a modified 16 piece tethered to the camera’s strap. Given the exacting tolerances of Lego there’s little risk of the cap accidentally falling off if bumped, and if you’ve got a bucket of bricks buried in a closet somewhere, the hack is pretty much already paid for. If you have multiple $200+ lenses you’ve probably got at least one with a different objective size on it.”]
Source: https://gizmodo.com/lego-lens-cap-holder-hack-brilliantly-merges-your-old-t-5978060