Aqua doodle eraser?
You may have heard about using an aqua doodle to erase the blue water erasable pen marks? Well I got frustrated having to refill that dang thing so often. I decided to find an alternative and this is it. A plain ol' glue pen that I simply rinsed out really well.
It has a marvelous felt tip just right for erasing the pen marks. I was surprised when the printing on the outside came off too. I do have to refill it eventually but this lasts a good long time.