small dc motor gearbox

This is set of objects and scripts allowing to build very simple gearbox.
I made it mainly for re-use of small and weak DC motors.
They are usually too weak to use with printed planetary gearboxes, so they require
very low-torque first stage.

Changing and choice of gears is very easy as gearbox core support is based on
two threaded rods.

It contains parametric (or at least easy to modify - openscad) motor holder ,
skate bearings holders (they are used to support rome reductor gears)
threaded rod holder (this is used to fasten whole gearbox to a housing)
and plastic planetary gearbox for hex shaft (this allows supporting hex shaft and allows power output via hex shaft - for example to peristatic pump rotor)

perhaps more elements will come later.
It serves as great toy and can be used in any slow motion high torque application .

many elements are copied from other people's designs , i hope i've included all credits , if not - notify me.