Added GoPro screw knob link

input/stuff.md

@@ -38,4 +38,5 @@ for p in mpages:
 * [Customizable AVR ESR meter case](http://www.thingiverse.com/thing:1625664)
 * [Quanum Trifecta rear landing gear](http://www.thingiverse.com/thing:1642129)
 * [Quanum Trifecta FPV top plate](http://www.thingiverse.com/thing:1642135)
+* [Customizable long GoPro screw knob](http://www.thingiverse.com/thing:1643650)