Touchstone is an open-source experiment design platform designed to help establish a solid research foundation for HCI in the area of novel interaction techniques. Touchstone includes a design platform for exploring alternative designs of controlled laboratory experiments, a run platform for running subjects and a limited analysis platform for advice and access to on-line statistics packages. Designed for HCI researchers and their students, Touchstone facilitates the process of creating new experiments, as well as replicating and extending experiments in the research literature. We tested Touchstone by designing two controlled experiments. One illustrates how to create a new experiment from scratch. The other replicates and extends a previous study of multiscale pointing interaction techniques: OrthoZoom was fastest, followed by bi-manual Pan & Zoom; SDAZ and traditional Pan & Zoom were consistently slower.