This is an original working prototype of a sub-irrigated planter (SIP) device I invented about thirty years ago. With little belief in the receptivity of the marketplace at the time, I chose not to patent and market it. Had I gotten a patent it would now be expired. Eventually someone did discover the same idea and I believe there is a patent.
The objective was to design a more cost effective and universal vacuum-sensor system that would work in any watertight container. The system works. I used if for a wide array of plants in my home, including specimen Ficus benjamina trees.
With advances in plastic molding technology, perhaps it is worth producing these things today. Anyone interested?