El Gratage Echo Knob (or something like it)

[Yroc006]

Echo Knob - El Garatge

The Echo Knob adds a low frequency oscillator to any pedal with TRS expression pedal input to add some motion to your sound.

elgaratge.com

Not sure if it’s possible, but it would be a cool addition to builds with an expression input.

 

[Feral Feline]

That's pretty cool, but I'd want a bigger more conventional pedal box and connect to the target pedal's expression input via a cable.
That would also allow a more robust footswitch, which would avoid the inevitable breakage and provide enough room for tap-tempo via Electric Druid's TAPLFO.

 

[Yroc006]

Right, lay it out in a way that you have it in its own small enclosure, or maybe a footswitch mounted utility board that you could use as an add on instead of putting in an expression input. I think there could be a few better implementations, but think the idea of what it does is pretty cool.