Here are a couple of things that've been kicking around in my closet for a long time now...
First, a pair of LF-1 rear lens caps. They're cemented together with what appears to be superglue and are very firmly attached to each other. This arrangement makes it easy to carry two extra lenses in your bag without having them move around independently - some people find this convenient, some not. $6 gets it shipped to your door in CONUS.
Secondly, an 12mm Vivitar non-AI F-mount extension ring. This is an old one with the ears. Everything moves smoothly. $10 shipped in CONUS.
First, a pair of LF-1 rear lens caps. They're cemented together with what appears to be superglue and are very firmly attached to each other. This arrangement makes it easy to carry two extra lenses in your bag without having them move around independently - some people find this convenient, some not. $6 gets it shipped to your door in CONUS.
Secondly, an 12mm Vivitar non-AI F-mount extension ring. This is an old one with the ears. Everything moves smoothly. $10 shipped in CONUS.