Your thoughts on this would be appreciated.
OK, my main thought is that you are way overthinking what I did and why.
This was at best a proof-of-concept experiment with materials at hand.
In my part of the world Lexan is called Perspex.
Is there a particular reason you chose this? more sound recorded? Clearer sound recording?
Because that's what Home Depot had in stock. I would have used acrylic or some other rigid plastic sheet instead of polycarbonate if that's what they'd had on hand. Lacking plastics, maybe I would have tried a sheet of aluminum.
Similarly, the dimensions of the device were dictated by the size of the pane I purchased.
We have some plastic boxes in New Zealand called Sistema and I was wondering if one of those containers would be OK to use.
Ideal for your fridge, freezer and pantry, KLIP IT® food storage containers are microwave safe, dishwasher safe and incorporate a rubberised seal and easy access locking clips.
http://www.sistema.co.nz/pages/KLIP-IT/KLIP-IT.html
Give it a try. There's no right or wrong way to build one of these, and this may yield better or at least different results. That's the fun part. Build one of each and try them side-by-side and see what the results are.
Here's one thing I have yet to try. You may have noticed that the tonal qualities of the rain sound similar no matter what the drop size or intensity is. Mainly, the amplitude of the audio changes. My assumption is that this is due to the resonance of the plastic plate.
I've wondered if using a piezoelectric film instead of the plate and element would yield different signals for different drop sizes. It might matter if the film were taut or loose, as well.