It is estimated that "about 15 Meccano model Differential Analysers were built for serious work by scientists and researchers around the world". More recently, building differential analysers with Meccano parts has become a popular project among serious Meccano hobbyists. An example is the differential analyser built at Marshall University, which is now used for educational purposes, in that a student not only solves a differential equation but also becomes the "calculator" by operating the machine, and so develops a better understanding of what a differential equation is.