Still in use by some machine shops, the target "Copymax" attachment was an ingenious adaptation of the ordinary "roller box" used on turret and captain lathes. A roller box is a long-used, self-contained attachment that holds a cutting tool and two or more supporting rollers. As the roller box advances, the work is supported against tool thrust by the rollers, so ensuring that a quick and accurate job is achieved.
The Target Engineering roller box was modified to carry a former made from a rectangular bar that had been shaped, very accurately, on one of its faces to the profile required. Each job required its own carefully-made former with all diameters made concentric - but they could be of any radius or even tapered. Despite the makers claiming that the formers were of the easy-to-make type, the reality was that considerable care had to be taken in their manufacture - the operating manual devoting several pages as to prepare them correctly. Hence, although a good idea in principle, it would only have been worthwhile making them for long, repetitive production runs. 
Target engineering also made a number of other machine-tool accessories.