A deformable drawing tablet in which contiguous longitudinal edge portions of a stack of individual elongate strips which are confined for relative sliding movement to form a drawing surface. Initial eddy current measurement values are obtained while an eddy current probe is positioned at an initial distance relative to the substrate sample, and terminating values are obtained while the eddy current probe is positioned at a modified distance relative to the sample. The use of syringaldehyde as a precursor to composites has the potential to reduce the cost and environmental impact of structural materials, while meeting or exceeding the performance of current petroleum derived resins. A brake element is mounted to the motor movable toward and away from the bearing for movement into and out of engagement with one of the bearing stop members.