This free download includes the 3D printable files for an open-source (OS) version of the Aroundsquare's Knucklebone skill toy. AO2's Knucklebone is the original hardbody knuckle roller. It is a simple skill toy that is manipulated with the fingers of one or both hands to perform tricks and patterns, or simply to pass the time. It is very discrete (unless dropped) and can be played in very restricted spaces, and in contexts where other showier skill toys may not be appropriate. 

The kbone is very appealing, not only for its elegant form and ergonomic design, but also, for the range of play styles that it enables. The rounded lines are perfect for spinning, flipping, and passing it between the fingers. It can be manipulated very casually and quietly like a worry stone, or can be used to perform a surprising array of freestyle flows, technical tricks, isolations, and even aerials. There are a handful of tutorials already available online at the AO2 YouTube channel, and we’ll be publishing more in the coming weeks to help get folks started. 

Note from the designer: I developed the original knucklebone circa 1989 when I was a kid in school. The crude original version was made from some kind of polymer clay (see photo). The new version is better suited to bigger hands, and has been designed for smoother flow and better trick potential.  

Knucklebone OS

The OS version of our Knucklebone is designed to be printed in two halves, and then glued together. The recommended print uses 50% infill, and requires minimal supports or none at all. The stock setup accommodates one 5/16 hex nut at either end to provide a little bit of weight, which is helpful for momentum based tricks. Huge thanks once again to Alexander German, the master of the third dimension, and prime accomplice in this project, for his outstanding work developing and testing the 3D files. 

The Kbone OS design is part of Aroundsquare's Open Source Toys project. As with our other "OS" designs, the Kbone OS design is made available under a Creative Commons license. Kindly note, however, that the license for the Kbone OS is different from the license for our OS begleri. While the begleri are available under CC-BY-SA (requiring only attribution and "share alike"), the Kbone OS is issued under CC-BY-NC-SA, adding "non commercial" to the list of rights reserved. This means that makers and modders are welcome to take, make, and remix the design provided they (BY) attribute the original design back to AO2, (NC) do not sell or otherwise use the prints or derivatives for commercial purposes, and (SA) make remixes available under the same guidelines. 

Please share your creations with #ao2os to help us all see the creations and iterations as they come!

Warnings: It is recommended that you play over carpet, couch, or the like, or outside. These toys can look almost tasty, so keep them away from young kids, and don't let anyone try to ingest them.