This thesis presents the results of an exploratory study of a tangible and a multi-touch interface. The study investigates the effect of interface style on users’ performance, problem solving strategies and preference for a spatial problem solving task. Participants solved a jigsaw puzzle using each interface on a digital tabletop. The effect of interface style was explored through efficiency measures; a comparative analysis of hands-on actions based on a video coding schema for complementary actions; participants’ responses to questionnaires; and observational notes. Main findings are that tangible interaction better enabled complementary actions and was more efficient. Its 3D tactile interaction facilitated more effective search, bi-manual handling and visual comparison of puzzle pieces. For spatial problem solving activities where an effective and efficient strategy is not important, a multi-touch approach is sufficient. The thesis uniquely contributes to understanding the hands-on computational design space through its theoretical framing and empirical findings.