, I had a drawer from an old cabinet that I just had to take apart and cut down to 13.5"w x 5.75"h x 18" deep. Put it back together with glue and 1" staples (air tools are priceless!). The face is 3/4"d x 6.5"h x 15.625". I got the 20" slides from Lowes.
To support the inside end of the rail, I glued & screwed a 3"x9" piece of birch plywood to a strip of pine board, then screwed that up into the counter top using 1 1/4" screws (I drilled the pine board first to avoid splitting)