It's a condensation surface on which vapours revert to droplets in a liquid state due to the colder ambient air-cooled temperature of the leaf compared to the gaseous medium and heat source below it (and therefore lower vapour pressure immediately next to its surface), allowing the condensate/distillate to be collected and funneled for disposal, recycling, consumption, and/or another stage of distillation, and, in this case, producing an increasingly concentrated azeotropic water-ethanol solution which you can sell for the big bucks.

…Slightly simplified, of course. You may in fact need multiple leaves over pots, or even a couple leaves bent into funnels/chutes, and possibly even one pot over another pot.

I.E., By definition, a leaf over a pot is a still, as long as you put it at a slight angle and leave a small hole at the edge so the distillate can be collected. ­— Again: Physics provides, money is mostly an illusion/labour optimization mechanism, and sheet metal might be convenient for this use case but literally everything is materials. … If your only thought on how to produce a technology yourself is "Who can I pay for this?", then, yeah, you're not thinking in the right lines to get there.

On another note, I like your username though. Did you know they do like pump jet lifting body action stuff in the air? Really cool.