Practice drum pad -> piezo drum trigger

I’m in the process of converting my REMO practice drum pad into a piezo trigger, as outlined in many sources online. Stupidly I can’t find the source at the moment, but I decided to go for a foam/metal disk with piezo/foam sandwich under the normal skin instead of using a fiberglass mesh as suggested elsewhere.

Has anyone of you got experience in this kind of build/conversion, and if so, what foam did you use? I ordered a “low density” foam sheet online, but now that it’s arrived I have a feeling it’s too dense and not “springy” enough. I will test it and report back, but thought I’d ask here too.

As an aside for the interested, I’m using Thomas Henry’s “trigger conditioner” schematic as a base for the piezo->trigger conversion circuit.