I'm very sorry to hear about your experience. I've tried this with both new and old Magsafe 1 connectors, and I was previously certain that this part offered a snug, but not overly-tight, fit.
While I unfortunately don't have a way to refund you through the Shapeways platform, I can certainly ship you a new part once I adjust for the apparent differences in your charger.
Could you let me know the model of your Macbook, and the model number of your charger? You can find this on the power brick on one of the sides, under the words "Apple Macbook Magsafe 60W Charger", and next to "Made in China, Model No. ######".
Feel free to reply in the comments here, message me privately on Shapeways, or email me at contact[at]lucaskwatson.com.