How can buy 1.Nope, I don't have any. I've meaning to order some from PartExpress but keep forgetting. It'll probably need 1/4" lb or so.
Yes, fits right under the floor. You will need to cut a hole and put a grille. I think a 1/4" plexi glass can be flush mounted to the top side of the floor.
I'm going to put this one up for sale. Material cost is about $60.00
Don't know for how much.