My friends and I went to a New York Comic Con party dressed as Gru and his Minions! It's a quick and silly costume and I was tasked with making the goggles so here's how I did it.
I made a template out of paper to fit my face and transferred it to 5mm craft foam. Here are the dimensions. If you get a regular piece of 9x12 foam, you can make 3 pairs of goggles from it because each eyepiece is 8x2. I don't know how long the angled side is but if you measure everything else, that won't matter. You obviously need to cut 2 of these out for both your eyes.
