Hi Chas, these are my shelves:
I find when the space between the top of the plants and the shelf above is quite small, there is already enough humidity in there, they don't need to be totally enclosed.
For deflasked and touchy species, i use a glass display cabinet and a couple of fans.
Everything watered from a common tray on each shelf, each shelf wired to an autopot tube and a single reservoir up above outside the basement. Whenever the water runs out the float-valve automatically fills more water into the trays.
With this setup everything is automated, air, humidity, light, water. I just need to refill the reservoir occasionally and watch everything grow.
Also the lights heat up the shelf above them, which is great for growing warmer species.