You can see my shop at my HP , did 12" x 12" rebar 6" pour and 12" pour where the lift was to be with anchor bolts ; anchor bolts for the lathe and mill locations . 4" of gravel , 2" of styrofoam , 1/2 " rebar with ( 3/4 " across the lift area of 12" deep x 4 foot wide and 12 feet in length )...