Hi Kayota I am not ignoring your info by any means...
I have look and read, I do see where your coming from however, I will try with out no plant to see what readings come up...
I would like to learn true, however I know the plant needs rain water, it needs to drain... and needs to have humidity... Which we all agree on ok
With the glass idea that has drainage you can see the water value, as to the humidity I am not sure of until I put a meter in and read it, ones on the way.
Because there would be a space at the top that allows it to breath... I could be wrong and the values would not be correct... as mentioned before every position is different which would give a different response.
The humidity I think would reflect the same nearly without a plant inside, if it does not work, then so be it I could simulate it and give you the readings to see what you think.
I also think that it depends on how something is engineered to achieve it's objective...
We had cart wheels once that gave us a bumpy ride, however now these have been much improve, since the cart wheel did it's job why reinvent the wheel, because someone did make it a better for it's purpose.
I hold my hands up, it's something I have never tried before... So it's a novel experience for me...
But if I could achieve the right enviroment why you think it will not succeed...
That's all I did not wish to offend anyone
:-( Noddy