Abstract: An improved apparatus for stamping impressions in materials such as uncured concrete, includes a base member having an upper and a lower surface and an outer periphery, the outer periphery having a shape which provides a repetitive keyed pattern which may be fitted together with tools of similar shapes in a plurality of locations. An inner blade, having a predetermined cross-sectional geometry, is coupled to the lower surface of the base within the outer periphery. An outer blade surrounds the outer periphery of the base member at the lower surface, the outer blade having a cross-sectional geometry which is a bisection of the cross-sectional geometry of the inner blades, so that two adjacent tools abutted one against the other produce a composite blade at their border which has substantially the same cross-sectional geometry as that of the inner blade. The blades and base member are made of a flexible elastomeric material.