Current in situ strain sensing techniques focus on determining accurate, time-histories of strain utilizing fairly complex sensing, compensation, data processing, and powering arrangements. A simpler and lower-cost strain sensing approach would open up more opportunities to use strain measurements to support engineering decision making. This work explores a fully mechanical, ultra-low cost strain sensor printed using additive manufacturing techniques. The accuracy of current additive manufacturing techniques are discussed, and the performance of the sensor in terms of accuracy, measurement repeatability, and batch-to-batch manufacturing variability are studied. An example of using the proposed sensor to measure transient thermal weld stresses is presented. Overall, the key challenge to such a sensor is shown to be the accuracy of pin and slot print features and the resulting slip and friction introduced into the sensor. A properly calibrated design printed with current state-of-the-art machines is shown to be capable of resolving strain changes on the order of one micro strain with good repeatability.