A plastic shim or other workpiece useful in the construction industry. The shim or workpiece is an elongated tapered hard plastic body incorporating qualities of a shim lacking in wooden shims. Each shim has transverse break lines so that segments can be broken off to adjust its length. For handling, a plurality of such shims are molded in a sheet with adjacent shims being spaced along their thinner sections but separably joined by longitudinal, break lines extending along their thicker sections, whereby the shims can be detached from the sheet either individually or in multiples. The shims may have pockets defining nailing portions of reduced thickness which minimize the grasp of nails by the shim and allow removal of nails without damage to the shim or adjacent wood and etching to avoid uncontrolled slippage.