This article presents a detailed description, and step-by-step process, required to build a small-scale wave energy tank demonstrator (Tiny-T). The system consists of an operative wave energy converter (WEC) with active control, representing the first demonstration of electronic WEC control at 1/100 scale. A key feature of Tiny-T is that the full demonstration system costs below €600. This document provides complete details on the materials, construction, and testing of the system, as well as aspects related to the appeal of the demonstration. As an experimental platform, Tiny-T represents a valuable resource for introductory research inquiries, catering to both high school and university-level studies. Overall, Tiny-T accessibility opens doors for a broader audience to engage with the promising potential of wave energy and real-time control technologies.