72 mm between centre of bottom bumps.
It's very easy on the pedal to accidentally switch modes between effects and volume, this prevents that.
Printed it at 25% infill, and it had just enough flex to allow a hard press to still switch modes, but if you wanted to disable that, printing it at a higher infill with less flex would prevent that. As it is, I assume this will be a wearable part over time as it gets stepped on and slightly crushed each time.
I have also included a version 1 that is thicker and presumably stronger. I did not print it, because it felt like it had extraneous material and I made it smaller so it would print faster as version 2.
The author hasn't provided the model origin yet.