Every time I sit down or bend over or sometimes just take a step near my Prius when I have the keyfob in my pocket, one of the dadgum buttons will get pressed by a fold of cloth and the doors will lock or the alarm will go off, etc. I just got a 3D scanner, so I decided the first practical thing to make from a scan would be a sheath for the keyfob to prevent the buttons from being pressed.
I used my new Matter and Form 3D scanner to generate the keyfob-scan.stl file. I used meshlab and netfabb cloud to generate the convex-keyfob.stl file which is the convex hull of the original keyfob-scan.stl file. I then used openscad to create sheath.stl by scaling up the convex hull and subtracting off the keyfob to leave a shell. It took 3 tries fiddling with the openscad to get a version that seems to work, but I think I have finished this project.
Details on the scanner and how I used it can be found at: http://home.comcast.net/~tomhorsley/hardware/matterform/matterform.html (Play Doh was involved :-).