Abstract: A ruler assembly comprising a ruler having a top extending along a ruler width and a ruler length. The top has an inner top surface and an outer top surface. The assembly has at least one side wall extending along the ruler length. The side wall extends from a side wall bottom edge to a side wall top edge proximal to the outer top surface. The outer top surface comprises a plurality of step surfaces, each having a step height measured from the side wall bottom edge to the side wall top edge of each of the plurality of step surfaces. In some embodiments, the inner top surface and the inner side wall surface define a ruler cavity configured to removably couple to an insert ruler.

Abstract: A ruler assembly comprising a ruler having a top extending along a ruler width and a ruler length. The top has an inner top surface and an outer top surface. The assembly has at least one side wall extending along the ruler length. The side wall extends from a side wall bottom edge to a side wall top edge proximal to the outer top surface. The outer top surface comprises a plurality of step surfaces, each having a step height measured from the side wall bottom edge to the side wall top edge of each of the plurality of step surfaces. In some embodiments, the inner top surface and the inner side wall surface define a ruler cavity configured to removably couple to an insert ruler.

Abstract: A self-leveling foldable saw horse including a trestle formed as a downwardly opening box, two pairs of legs, each of which has three working surfaces for leveling the pairs of legs, stably supporting the weight on the trestle and enabling rotation of the legs from a closed position to an opened position and two rods for supporting the legs. The first operating surface on each leg of a pair of legs is in contact with the first operating surface of the other leg of its pair and the second surfaces of each leg of pair are in contact with the underside of the top surface of the trestle when the saw horse is in the open position. Exerting pressure on the top surface of the trestle causes sliding adjustment of the first operating surfaces of each pair to level the trestle and stably support the saw horse on uneven surfaces. Two saw horses can be attached together in a compact, efficient manner with handles to transport the pair of saw horses for use on uneven ground surfaces.