When my twin girls were 3, we wanted a light-weight costume that they could wear but that would also play nicely into the twin them.  I started thinking of things that only come in pairs and eventually arrived at a pair of flip flops for my concept.

I didn\’t find anything online at the time that matched my vision, so we started with some pliable craft foam, and cut a front and back.  I spray painted the back black and covered the front in blue fabric so that I could insert/hide my straps.  I used a cute wire ribbon for the toe straps and connected the back to the front with some yarn covered in felt so that it wouldn\’t rub their shoulders.  I put a silk flower in the middle to spruce up the look and we were done!  Super simple, light-weight and fun.  They actually wore this costume again this year for a portion of Halloween night because they like them so much.