I’m using an EHX 3-button, which works fine. I would expect most 3-button switches that are *not* the Strymon switch to work with the H90. (I’m also unclear on whether the Strymon switch works with non-Strymon products, or the other way around. I should probably plug the EHX switch into my Volante and test the idea.)
I had a standard aluminum enclosure and two standard non-latching (momentary) footswitches hanging around. Nothing special. I just wired it up and it worked like a charm.