i'm trying to get some info on a custom shower i'm trying to install. i would like it to be all tile, with a frameless glass enclosure. i have a pretty good idea on how to build the shower pan floor with some plywood and 4x4 or 4x6 border. what should the drainage elevation be? the plywood should be elevated somewhat to allow water to flow to the drain in center of the pan, correct? what plywood thickness would you recommend, and should i use different width spacer/runner boards under the plywood to support and form the slope? also, should the plywood floor frame then be "hot-mopped"? then covered with cement board? then tiled?