Reflection jig for Science Olympiad - Optics

This is my first attempt of making a jig for my middle school students to use during the Optics event of Science Olympiad. In that event, they are to place mirrors and predict where a laser beam will go. They have only a few minutes to set up mirrors, so I was thinking of methods for them to be accurate and faster on their setup. 

This jig has two arms that pivot at a base. A slider keeps the angles of these arms the same. In other words, the arms represent the path of the reflected laser when it bounces off the base. The base is flat such that it can be placed against the flat mirror surface. 

Note: there are small slits at the base of the arm if you wanted to print extenders (or use cardstock) to project the arms more.

Other items needed: piano wire and drill bit (sized for wire).

Assembly: I used a small drill to pilot the tiny holes (0.7 mm) after printing as the holes will get clogged. There is a piano wire (~0.5 mm) that I put through the pivot point. First, drill the holes through the frame, top arm, and bottom arm (I turned the drill bit by hand with my fingers). Second, bend the piano wire creating a small “L” at one end, sticking out a few millimeters. thread the long end through the bottom arm (with the “L” elbow situated inside of the bottom arm), top arm, then the frame. Pull and bend the wire to keep everything in place - then snip it. Align the slider and put into place. 

There is nothing keeping the slider in place, it may fall out; but, in my experience, it stays in pretty good. Before assembly it is a good idea to smooth out any bumps with a razor. 

The span is about 20 degrees to 140 degrees. There is some error ('wiggle', etc.) near these extreme angles. 

Printed on Prusa MINI+, PLA, 0.4 mm nozzle.