Abstract: A trial tool for injection moulding is made by subjecting a cast Zn alloy tool blank to rapid EDM, using a first electrode and a relatively large EDM gap, to produce a coarse surface closely approximating to the required shape, and then subjecting the coarse tool to slow EDM, using a second electrode and a smaller EDM gap, to produce a trial tool having an operative surface of the required shape. A production tool is then made by subjecting a cast steel tool blank to rapid EDM, using the second electrode, and then subjecting the coarse production tool to slow EDM, using a third electrode.