This work describes the design and implementation of EE40LX: Electronic Interfaces, the first large-scale analog circuits laboratory hosted offered by edX. EE40LX revolved around constructing a robot, emphasizing hands-on circuit building over circuit analysis to keep the course broadly accessible. With over 80 thousand students from over 190 nations enrolled across one year, this course is the largest and most distributed open analog circuits laboratory of its kind. Its sheer scale necessitated careful design of the robot project and a robust rubric for peer grading. This paper presents a detailed description of the course and its instructional design. In total, 856 robots were built and over 2233 students earned a certificate of completion, a 2.5% overall completion rate. Students completed voluntary surveys at the beginning and end of the class to provide insight into the approaches that independent learners take when studying electronics at home. These surveys indicated that the peer review process resulted in fair grades and also that the course was well received. Other analytics provided by edX suggest ways to improve the completion rate; particularly by offering continuing education credits, introducing more simulation exercises, and simplifying the hardware acquisition process.