A small vice was purchased and reworked to make it very free in use. The leadscrew “collar” was freed to enable the moving jaw to slide independent of the leadscrew when opening. The moving jaw was then attached to a long lever hinged at floor level. In operation the client opens the vice to just wider than the workpiece, then positioning the work with his “good” hand he lightly closes/clamps the work by pressing on the long lever with his knee. He then tightens the vice with the now free hand.
The client has regained a level of independence and is now engaged in expanding his railway layout with a high degree of satisfaction and dexterity.