@Floyd
My first attempt was with the same top, and instead of making a new one I just cut those pucks from a different (softer) foam material. The first time it held clear Solo cups that contained soil and a strip of cloth to wick moisture up into the soil.
There was no bubbles, just a wick into each Solo.
I raised the wick higher and higher in the soil until I had the moisture where I wanted.
I liked the original concept but wanted to try just bubbles once. The next time will be a better wick system.
Here is a small example I saw on here. Mine is the same concept only on a larger scale @beardedvet222