play kitchen knob

My friend rosebud wanted a "clicking knob" for a play kitchen. So there it is!

Knob diameter: 8cm (since V1.5). Photo is a prototype 50% size, **but I think 50% is suitable for the most applications (4cm knob diameter)**

Assembling: just put the shaft of the knob into the hole of the bottom. But be careful: the "click blade" has to be aligned to a space between two teeth of the gear while putting the two things together (see the corresponding picture).

##### V1.5 2018-12-19 - final
* resized knob to the size of the back => perhaps less stress for the "click blade" because its longer now (*thx rosebud for the tip!*)

##### V1.4 2018-12-18
* made some optimizations on "click blade" shape and dimensions

##### V1.3 2018-12-17
* made click blade" thicker and broader
* made the "gear" of the bottom broader

##### V1.2 2018-12-16
* added rippling to the knob for better grip

##### V1.1 2018-12-16
* shortened "click blade" a bit an rounded the tip
* enlarged the marke