Sharpies not included.
Having used Robeez for my kids, I can vouch for how great they are in that the elastic band prevents them from getting kicked off. Another thing I loved about these slippers was that they're made out of leather and can be thrown into the washing machine or cleaned with a damp cloth. This is esp. important for those parents who have crawling or walking wee ones.Would the ankle strap work the same way for the felt slippers?
Wee Pereas has Robeez look-a-likes with elastic backings. And I do think the ankle strap would work the same as an elastic. I love the Wee Pereas ones because they're reversible, too. You could use leather, suede, waterproofed cotton, etc.