As cool as butterfly knives are (with all the tricks you can do), sadly, they are illegal in most places. Solution? Switch the knife for a comb! Now you can whip out your comb in style, maybe even pull off a few tricks before giving your hair that combing it needs. Best of all, it's printable from your 3d printer!
Warning: Design is in beta. Will hopefully get around to improving the design for better assembly and function.
4x M3 washers
2x M3x10 bolts (or substitute with bamboo skewers like I did)
2x M3 nuts (if bolts are used)
Simply hinge the 2 handles with the comb part, using 2 washers on each handle as spacers (see image). Make sure to orient the handle such that when closed, the comb sits nicely in the groove of the 2 handles.
Fixed up the sizing of the comb part so that it does not wobble when extended. Also reduced the width of the teeth (found it works better for combing but please let me know if it was better before).