We propose a set of customizable, easy-to-understand, and low-cost physiological toolkits in order to enable people to visualize and utilize autonomic arousal information. In particular, we aim for the toolkits to be usable in one of the most challenging usability conditions: helping individuals diagnosed with autism. This toolkit includes: wearable, wireless, heart-rate and skin-conductance sensors; pendant-like and hand-held physiological indicators hidden or embedded into certain toys or tools; and a customized software interface that allows caregivers and parents to establish a general understanding of an individual's arousal profile from daily life and to set up physiological alarms for events of interest. We are evaluating the ability of this externalization toolkit to help individuals on the autism spectrum to better communicate their internal states to trusted teachers and family members.