This is a minor modification of Johann's Kossel extruder, which makes it parametric allowing to fit different spur gears or pulleys, moreover, if required, it adds a mounting bracket. Do not download the STL file, most probably it will not fit your requirements, donwload instead the OpenSCAD file to generate your STL.This remix makes possible to use different spur gears or pulleys. So it is possible to generate the original Johann's extruder, as much, by changing few easy parameters, to adapt it to fit different pulleys with different diameters. It is also possible to specify the diameter of the screw of the pneumatic fit. One extra feature is the ability to choose if the extruder needs to be printed with an additional mounting bracket. The OpenSCAD file allows modifications to the following parameters: new_rad is the radius of the pulley / spur gear pn_rad is the radius of the pneumatic fit screw pi_rad is the extra radius for the pulley / spur gear indent pi_h is the height of the pulley / spur gear indent hmount is to enable (1) or disable (0) the mounting bracket Once you modify these parameters you will have a ready extruder to fit your gears.