This is a case (or holster) for a Garmin Montana GPS. It is designed to be flexible in how it attaches to your belt, strap, or whatever. Until this case there was no Montana case that protects the screen against both damage and accidental touches. This case is more of a holster that can attach to your backpack strap so it is easily accessible but still protected. Solidworks files are included. Print both pieces with 0.1mm layers, 0 extra shells and 100% infill. I used PLA, but ABS should be fine. The reason for 0.1mm layers is to avoid needing supports, and a smoother finish is desirable. I would advise against using rafts, since if the raft doesn't detach from the print cleanly it might interfere with the gluing process. Carefully glue the two pieces together (I used epoxy). This is critical for the strength of the case, so spend the time to do it correctly. File/Sand/Smooth the inside of the case. These surfaces will be rubbing against the GPS, and will wear marks into it. The smoother you make it, the longer this will take. However, it WILL happen eventually so don't say I didn't warn you! Thread some 3/32 inch diameter elastic cord through the eyelets. Pay attention to how it is threaded in the pictures, since this offers some fault tolerance should the glue/joint between the two pieces fail. If you jam a round toothpick into the eyelet with the elastic it will hold the elastic tight while you tie the knot. You will need to play with the elastic to get it tight enough to keep the unit in the case, and the toothpick will also make this task much easier. You will need three straps. Two that are 10 mm wide, and one that is 20 mm wide. I used these straps from Sea to Summit, http://www.seatosummit.com/products/display/155. I didn't use the straps with the "hook release", since they are not as secure if the straps are slightly loose.