The Dutch designer and dad Floris Hovers presented Flessenboot at this year Milan Furniture Fair. It is a sailboat toy kit that comes with a colored sail, mast and rudder. You supply the empty shampoo bottle on which you will strap the other elements.
Hovers got the idea while watching his daughters play with bottles in the bath and the memory of a toy boat he created on the spot six or seven years ago on a camping trip to entertain little boys playing by a river. I got the impression that you can purchase the kit directly from him but you are better to ask a friend fluent in Dutch to check his Web site.