A stretching device has a housing, a first clamping member attached to a first portion of the housing, a second clamping member attached to a second portion of the housing, a first insert mounted to the first clamping member, and a second insert mounted to the second clamping member. The first insert and the second insert protect workpieces to be clamped and gripped therebetween. The inserts are releasably mounted to gripping surfaces of the clamping members.