I needed something to keep up with my pen for my Samsung Tablet. I debated on building a custom holder for it but I have seen these things elsewhere and decided to print one.
This thing will insert into a standard headphone jack on any cellphone or tablet and has a place to string a lanyard through it. You can use it to attach whatever to your device or use it as a dust cover.
3D Printed with MakerBot Replicator 2. This file already has break-away supports. Print on 100% infill. Included Sketchup file in case you want to remix. Rendered with Maxwell Renderer for Sketchup.