Rules for Tools seeks to uncover historic and tectonic rule sets to parametrically process current predicaments of materials and technologies. The proposal investigates two geographically and intellectually relevant design-builders: Francesco Borromini and Pier Luigi Nervi. While both architects worked in disparate historic periods, both created novel spatial arrangements using specific materials and modes of translation from design to construction. The main design modes used were subtractive through stone cutting and additive with reinforced concrete. Borromini’s stones were assembled into flowing forms which disguised individual building elements. Nervi stacked cast elements which highlighted the incremental, individual parts. Their construction techniques and practices will inform my own work carried out in Rome in light of new material innovations, advanced manufacturing, and quickly evolving industrial robotics.