Isoangular curve demonstration

I designed this for a demontration in my class of the isoangular curve (I think is called like this :\. The name in Spanish is "arco capaz"). It is made by 3 pieces. A base and two mobile "arms". You wil need 2 M3 bolts with a square nut (I used Mecano set) and any kind of rod or screw of 3mm aprox. to use as lever. With a soldering iron you can fit the nuts by heating them while you press with the iron.