I've been looking for a cheap around-the-house solution to losing my 49mm Minolta lens cap, and found out that if I cut the top off of the flip-up lid of the new (hideous) style of Folger's Instant 3 oz Coffee, it fits well enough. Probably a little piece of tape or felt would make it more snug, but it does work as is. Then I discovered that because it has 2 different-sized lips on the under side it ALSO fits my 58mm Canon lens, and it fits that one superbly and snugly, snapping into place. After googling I learned that other Folgers lids have been used for lens caps for many years (didn't know that). But this is a fairly new style of lid, shown below. If you don't like red, get the green decaf versions.
If you hate instant coffee, you can send the contents to me because I actually drink the stuff.
The larger 16oz size will probably fit a couple of larger lenses. That one is just a hair too small for my Apo-Nikkor 480mm
I agree about Instant Coffee --- aaargh. And I applaud somebody trying to save a couple of bucks. Never knew when that next olde camera, that you want but have no earthy need for, will surface.
To complete the upcycling, why not then just paint the whole bottle black, cut up some 35mm strips and make it into a miniature pinhole camera?
Then nothing gets wasted.
If you cut it from the top and paint the bottle black, you can put it on your lens and it will look like a big lens.
My Brother recently gave me a Rollei 35 for my birthday and it had a milk jug cap for a lens cap.