Soft Release Buttons

Concave and Flat Soft Shutter Release Buttons, haven't printed them yet so I'm not sure how well it works.

Thanks to [Schlem](http://www.thingiverse.com/schlem/about) for providing the tapered ISO 6053:1979 thread in his [S.C.R.A.T.T.](http://www.thingiverse.com/thing:186443) project.