Redundancy - When It's A Good Thing.

 In this case I'm talking about redundancy in switching - when something important can be switched by independent switches so if one fails, the other still works.

For example the Stylus' cooling fan can be switched on by a temperature switch on the engine, one on the radiator, or by the ECU. I did have something similar for the brake lights, there were hydraulic switches on both front & rear circuits, plus I'd fitted a microswitch on the pedal as that switches as soon as the pedal starts to move, rather than when the pressure builds in the system & might just give a fraction of a second more warning to someone behind me.

BUT, the lever on the microswitch broke a while ago & now I'd taken one of the hydraulic switches out (it was the high point in the system & may have been causing the bleeding issue), that left only one switch, so I looked at re-instating one on the pedal. 

I've used the 3D printer several times when making parts for the car - this time I actually used the 3D printer, because I used a roller microswitch from a filament sensor. I made it fit the bracket from the old switch, but the bolt head the old one hit to switch it was too small. Looking through the pot of left-over fasteners I came upon a furniture bolt with an M6 thread to match the riv-nut in the roof of the footwell, a square to lock into the wood & a smooth domed head - perfect - NEVER throw things away.

You can just see it above the top left of the pedal, with the microswitch roller touching it. Obviously the important thing is to make sure nothing can restrict the pedal travel, so the bracket is very thin soft aluminium & the lever for the microswitch is very thin, so they'll both just crush if the worst happens, but in normal use, they're not close to anything.