What we do......You need some 2' rebar, one for each corner set them to grade using a laser level, factor approx. 2% grade or 1/4" per foot slope. Tie string at top end, pull tightly to opposite end, now using 1" gas pipe and straight screeding boards pull the sand over top of pipes at required distance below string. No dips or valleys unless your pipes are crooked.Completed a 20' x 30' paver patio in the fall for a customer and I think we spent too much time manually leveling the patio. Does anyone have any tricks/technology for leveling a patio while maintaining the pitch that they wish to share?