I was reading a book about the best math writing of last year (2014), and came across an essay about the number of types of KIlein bottles, and was amazed at the variety of the things!
Here are some to look at:
https://www.google.com/search?q=klein+bottles&biw=1024&bih=631&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoA2oVChMI3a6WocWkxwIVFjaICh03_AAo