No beauty, but practical alternative ...

The inner ring is made of relatively soft plastic and relatively deep, but why one can also passable attach the lens cap when folded. The rubber is a little labbelig, but still it does what it should, without my Olympus M.Zuiko Digital 45mm 1: 1.8 lens silver causing vignetting (also not fully extended).

Good article for results-oriented photographers who do not mind the slightly cheap feel and workmanship.