This was definitely a fun project, but too messy with just two days in the vinegar. I made 3 dozen for Easter and included food dye in the vinegar and they became really pretty colors. The membrane was about as thick as a balloon (some much less than that), so the kids could barely play with them before they would break. Then the dog choked on the membrane. I would try this again leaving the eggs in for a week to see if it would make them stronger.
The kids really enjoyed doing this experiment. When we placed the eggs in the vinegar, they began to bubble and foam. The eggs kept floating, but it didn't matter because once the bubbles built up on the bottom, the eggs flipped over. They come out a weird yellow color because the vinegar dissolves the shell and toughens the membrane. There is nothing to 'peel' so I think step 3 is a little misleading. They feel rubbery and kind of gross but we didn't think they looked like eyeballs because they aren't clear enough to see the yolk inside. The inside of the egg remains liquid so be careful that you don't squeeze or try to stretch the egg too much! My son learned this the hard way! ;) Also, you have to be careful where you put them because the insides do seep through the membrane and make a drippy sticky mess. Thanks for sharing!
This is another experiment that I have done with my students. To me, it really really stinks, but I am picky about that kind of stuff. Of course, that means the kids love it though :) Thanks for sharing!