This is a remix of http://www.thingiverse.com/thing:605360 Parametric Spool Hub tweaked by several people and now by me to fit the NinjaFlex Splash Spools we are selling. Since I have a kit printer I didn't have to use some of the advanced features of the design. Also check out this other Splash Spool Adapter here: http://www.thingiverse.com/thing:1034541Starter quantities of NinjaFlex can be purchased from us via our website, eBay or on Amazon search for "Splash Spool" I used PLA to make this. You may want to increase the height which is on this line (h=1) : cylinder(r=spool_hole_diam/2 + 4, h=1) to make it a little sturdier. I am planning on making a bunch of these so I took it down to h=1 to save on material and print time. Someone had a suggestion to use a rubber band to string the two halves together if they pop off. I did not have any issue with them popping off.