Kitbashing is a modelling term. In kitbashing you start with say, the nose cone from a model rocket, the tracks from a model tank and the radiator from a model truck and combine them to make a new original design. Kitbashing allows you to start your project a few steps along the road of creation, you don’t having to make absolutely everything from scratch.

My plan is to create a set of ready to print parts to 3d kitbash with a focus on robotics and automata. Here are my first tentative steps:

Starting with a test grid to mount some gears.

I’ve printed out a 24 tooth and 8 tooth gear with standard size axle hole (6mm FYI)

First draft of the axle stub was a single parts but I’ve found that printing it in two parts works best when adding the split pin legs.

The two parts push fit together like this. 

The gear then fits onto the square shaft leaving the spit pin legs to clip into the test grid. It has a nice positive action clipping into place firmly but is still easy to remove.

There probably needs to be a range of different axle lengths. This one is long enough to accommodate two gears.

I might need to add some sort of spring into the design of the axle so that it is easy to add and remove gears. Something like this perhaps?

The parts pull apart and pop together nicely and allow different gear trains to be constructed  easily. I reckon this is a promising start.