The primary means of communicating the design to manufacturers is by drawings. A scale drawing is an accurate plan with elevations and sections nowadays generally done using Computer Aided Design but sometimes drawn neatly in ink or pencil on to paper. The client who comes to the designer with preconceived notions of the solution will stultify design; the client who expects an invention from the designer when he has produced no brief at all is asking for the impossible. The design has to travel from the designer's mind to the myriad of other professionals who are going to make the exhibition possible. The person who brings together any contractor with any designer is essentially the estimator, for it is the competitive price that wins the contract. Special-effects contractors are supervised by the designers or production managers and, when there is one, the supplier of the technical information that the special effect is intended to communicate.