The project has uncovered a rich tradition of constructivist thinking in classical geometry. Anchoring geometry in construction devices that generalize Euclid’s ruler and compass was a way of ensuring rigor, not dissimilar to the motivations that led to a revival of operationalism, positivism, constructivism, and intuitionism in the 20th century. With this lens we have uncovered new layers of meaning in mathematical works of antiquity and the 17th century. With our reconstruction of the underlying research program, the specific technical choices of these works take on a broader significance and are seen to be part of a coherent dialog.