What do you use for a humidity dome?

I'm embarking on my first DWC grow here shortly and was wondering what you guys use as a humidity dome after placing the germinated seed in your prefered medium?

I plan on using a starter plug with hydroton in a 3 inch net pot. I was wondering how i can keep the humidity up diy style.. suggestions?

I'd like kind of the same answer here.

I've used the domes you get with the rockwool cubes and tray etc...

What i'm looking for is something to fit over my homemade ez cloner which can come in all different sizes... thus bringing us back to happy4lifes question.

can you use the plastic sheeting from the hardware store? like 2mil stuff? not sure this would let enuff light thru