I'm looking for something that will allow me to easily attach/detach screw in filters, similar to a lens cap.
I couldn't find anyone making this product right now...
But it was patented back in 1996: http://www.freepatentsonline.com/5528328.html
Maybe it's possible to mash one together with the right lens cap and step up ring..
Edit: Looks like these caps will work: http://www.bhphotovideo.com/c/search?Ntt=snap+on&N=4291599900