Flexure slip clutch

This is a flexure spring based friction clutch that can be used in mechanical designs as a torque limiter or a gear or motor saver.

The maximum torgue before slippage can be increased by increasing the `tight` parameter or the `height` of the mechanism. These and other parameters can be customized freely (in OpenSCAD as the on-line customizer doesn't seem to work). The example application is suitable for testing and does not by itself attach to a second shaft.

PETG is a preferred material because PETG springs retain tension over long periods.