Robby has an anatomy similar to that of a stick figure, with lanky black limbs. He has black fluffy hair with a pale blue and red propeller hat. He also accessorizes black glasses. Like most characters, he lacks a neck. He sports a black collared T-shirt, with a large front pocket.

He has three claw-like fingers and often wields a wrench in his left hand. His attire is finished with black shoes. Robby is an ordinary child among the students, who is quite attentive to learning. However, it seems he can be chaotic at times.

It can also be noted he may like building stuff, as he wields a wrench.