Summary I'm always losing my ink pens at the office. I lay one down somewhere, and then I have nothing to write with the next time I need one. Where do they go? I needed a tracking device. I thought I'd use some NinjaFlex filament I bought from Maker Geeks http://www.makergeeks.com/ to band my pens so I could recognize them if I saw them again. Much as scientific researchers do to track animals in the wild. I measured various writing utensils I had on my desk and used 123D Design to make flexible bands to fit them. If you need a size not listed, they can be scaled to fit in your slicer software. Print Settings Printer Brand: PrintrbotPrinter: Printrbot PlusRafts: NoSupports: NoResolution: .3mmInfill: 100% Notes: I slowed the bot way down to 10mm/sec, no retraction. I printed at 230C on a Kapton bed wiped with a glue stick heated to 70C. I use this NinjaFlex adapter I found http://www.thingiverse.com/thing:439617 to coax the filament into behaving itself. How I Designed This Designed with 123D Design I started with a cylinder 4mm tall and 2mm larger than the ID of the band I wanted. Then I created another cylinder 10mm tall and the exact size of the ID of the band I wanted. I then snapped the smaller one onto the larger one. Using the move tool I moved the smaller one down through the larger one. I then used the Combine/Subtract tool to cut the smaller one out of the larger one, creating a band.