I like that idea of a pump on a timer, but see no need for weighing it down too. the wine you pump over will weigh the cap down.
my only concerns are ..
Make sure that all external surfaces that contact the wine (the gajillion hole pipe and your eductor) are placed inside inside your primary fermenter. I would then loosely cover the whole works with a thin plastic (unused) drop cloth.
I would make sure that this only happens during active fermentation. Without the positive pressure of co2 being produced, you could be encouraging spoilage.
When I incorporated the cap plate, I was just thinking of options for better / more skin to juice time versus time possibly drying out or being exposed to air. I would consider it a modular piece that could be there if you wanted but doesn't have to be. I was intrigued by a number of wineries that use them and articles about submerged caps.
@CDrew I too, at the moment, just punch down the cap but then there are 16 hour days at work where the cap should have been punched down and I couldn't get home to do it so this would be another way of cap management. Plus as @winemaker81 eloquently said, sometimes it's just fun and satisfying. I'm a project guy and very curious so figuring this out to fruition would be very satisfying.
@Ajmassa my first design had a 'through the wall' drain pipe at the base like you suggested. Then I thought of a Koi pond filter I originally built that had more holes going through the container than probably the definition of 'container' meant... LOL. To minimize the possibility of leaking (especially from a plastic container) and to minimize cleaning/sanitizing points, I thought of the gajillion hole pipe method I first saw on your postings and it clicked for me. I agree this could be adapted for delestage. It could even be used for delestage with seed removal but I think that using conical containers for primary fermentation might be better as you can easily remove the seeds through the bottom drain.
@JohnT excellent points. I would only use this during primary until pressing. I read an article somewhere here (I think in the 'Closing the Gap' forum) about how different wineries schedule their cap management cycles and would mimic those as best as my notes remember. I believe early on it was twice a day until a cap began in earnest, then it went to three times a day, then as the fermentation closed in on finishing it went back to twice a day. Easily set on a timer, and could be done through the night as well. And of course enclosed to some extent because of those (explitive) fruit flies.
As this progresses I'll keep everyone posted. Sounds like a good winter project...!