I just got a Structure.io Sensor. I printed the awesome iPhone 5 case http://www.thingiverse.com/thing:368570 and immediately realized that I wanted a cover to protect the glass front. So I took the CAD model from the SDK and whipped up a little cover in OpenSCAD to print and share. It snaps in place when printed in PLA. If you print in ABS, you might need to shrink by 1-2% to get a tight fit. It's quite thin, so you might as well print 100% fill. Print it flat side (where "structure" is written) down, as it's oriented in the STL file. The text is hollow for the first layer or two.