A mod to the 15mm design from "peter m". I am using a modified Replicator 2 (heated bed) and have had some issues with dialing in on the PETG. As per a request from another commenter I brought the design into my solidworks and added a number of fillets and chamfers. My test print came out well. Enjoy.
Since I am running a Replicator 2 probably not all that useful for you. Contact me if you are trying to use PETG on a Rep 2 with a heated bed.
The author remixed this model.