The models posted here are three .stl files that can be printed in PLA to make a positilve molds for silicone compact tension molds following ASTM E647-00 Standard Test Method for Measurement of Fatigue Crack Growth Rates.  The molds can be used to form circular and rectangle test samples of various materials including, but not limited to resin, epoxy, and cement.  The parts fit into a frame that allows for easy mold production.  To download the parametric files in OpenSCAD and modify the sample size while still preserving the sizing ratios please visit the link below.  

https://github.com/dporter535/Compact-Tension-Mold