In the Montessori system of education, it's believed that children experience these three things below the age of four: An interest in small objects, sensory refinement, and order. Greek toy designer Matolaki thus designed this mechanical wooden toy to slot into the curriculum:

"This wooden pull push Montessori Toy is ideal sensory learning set for imagination expanding and will help gross and fine motor skills development. 100% Eco Friendly Toy, no plastic used; ; weights only 340g /0.75 lbs, a perfect travel set toy!"

In real life, they're a lot bigger than they look in the product shots:

They're selling for about $50 on Etsy.