Growing up I watched a lot of Batman and ran around pretending to fight crime. So of course, my dream tool is a collapsible batarang designed to thwart evil-doers. The MOVEin3D contest seemed the perfect time to act on this life-long dream and hopefully provide a useful tool to all other crime fighters in the 3Dswym community.

I designed the batarang as an assembly in Solidworks 2014 pre-release.  Using planar sketches I was able to create the outlines shown above and then chamfer and fillet the edges to a more realistic shape. I quickly realized however that I had overlooked how the batarang would impact itself when collapsed. If the wings were to remain flat, the inner points would impact before the far tips.

To fix my error, I went back through the design tree and created an extruded cut to allow the central parts of the batarang to pass over each other while keeping the outer parts aligned on the same plane. To allow the batarang to spin between two positions, I came up with a notch system to lock the assembly in the open and closed configurations.

The Top/Left part of the batarang has two sets of notches aligned at the open and closed positions. The button in the center can be pressed downward to lower the locking piece and allow the Top/Left half to rotate freely. Releasing the button, the spinning half will be stopped when it rotates through either the set of notches.

(I'm not sure if the above image is large enough to view, but you should be able to click for a larger version.)

Although shown as three parts, the actual assembly is only two. The central button is connected to the Right/Bottom half by a spring. This spring allows the button to press upwards during the spinning motion and immediately lock the assembly once either set of notches align. 

I believe this is a great use of 3D printing technology because I am able to create a unique mechanical assembly for use in a niche product and I am able to make it entirely with a tool I am familiar with, 3D modeling. Also, because it is a 3D file, it can be printed at numerous sizes allowing you to have any size from desktop prop to full-size batarangs.

So that's my design and I hope I explained it well. Please let me know if there's anything I can elaborate on or if you have any other questions. Thanks for reading.