Holder for 18650 batteries for the Nerf Stryfe.
Disclaimer: If you have no respect for Li-Ion batteries and short them out, they will quickly teach you respect... Also, do not leave AA batteries in their battery tray when using 18650s in this holder unless you like bad surprises...
I had spare 18650 batteries on hand and wanted to be able to use them to jazz up the voltage in the Stryfe a little (8.4v with the two 18650s vs 6v with AA Alkalines (or even 4.8v with rechargables)) without having to do a bunch of soldering or the need for springs and/or extra screws.
With this design, you only need the single printed piece, two 18650 batteries, and approximately 6" of wire (I used car wire since I had it handy).
Presuming you already own the Stryfe ;) , you re-use the screw from the stock battery cover for this one.
I borrowed a couple of designs from here (http://www.thingiverse.com/thing:1351511 and http://www.thingiverse.com/thing:195543), chopped them up, added some holes and chamfers, and combined them to make this holder. I thank jelrebel (who remixed a design by ssaggers) and anode505 for their designs. :)