What is a calculation, what is an algorithm? In 1936, Alan Turing provided an answer to these questions by defining what is now called a Turing machine, that is to say an abstract mathematical model that gives precise meaning to the intuitive and ancestral notion of computation, and which is particularly suitable on the theoretical level to address questions of computability and complexity. Can we imagine building, only with Lego bricks, a very real “Turing machine” and thus “seeing” a calculation? This is the challenge we will discuss in this talk.