This article outlines an extension exercise that is based on the elementary geometrical constructions in the National Curriculum. The challenge for students is to organise and execute an extended construction. The hidden, parallel agenda is proof, for the teacher's role is to convince students that they "must" succeed and that doing so is a measure of their draftsmanship skills. The author suggests an appropriate level is Year 10, but it will be accessible to a "good" Year 9 group, and still useful to many Year 11 groups. This article presents a comprehensive outline of the theory, a suggestion for how a workshop may be constructed, and an activity sheet for students.