Disclosed herein is an apparatus and a method to use such an apparatus for visualizing the contraction stress from curable materials. Particularly, a simple test device has been designed and fabricated and a method of using such a device, which allows a user to easily distinguish the curable materials that can generate contraction stress in different magnitudes. More specifically, the present disclosure provides a simple and effective way to make the complicated contraction stress due to polymerization (curing or setting) visualizable and audible.