A new Prusa I3 Geeetech 70 mm customizable cooling fan. With switch

I wanted to redo the fan with a measurement of 70 mm because I saw that the 40 mm were not sufficient. With this the final needed results is better. Sorry if my English is bad and if my source program OpenSCAD, is worse ... I am novice.
I wanted to insert a switch since the Aluminium Prusa I3 geeetec with Sanguinololu not handle ventilation. This is handy when you print in ABS, and do not need so disconnect the cable.

Ho rifatto una ventilazione con ventola a 70 mm in quanto ho verificato ch