Simple electric motor demonstration kit

Years ago my son brought home a very simple electric motor made of a coil of wire supported on brass contacts above a D cell battery holder. I thought it was quite an elegant little demonstration. I was recently asked if my company could support a STEM night an an elementary school. Since we build a lot of products with electric motors, I said I'd provide an activity where the students could build and take home their own electric motor. They also said to plan for 150 kids. Those D cell batteries were going to be very expensive in that quantity. This is a variation of a C cell design I found on line using safety pins to support the coil and a rubber band to hold it together. It had no base and just rolled around on a table. I thought the project would be improved by a base, and C cells were still too expensive. An AA battery fit my budget but it is too small for the rubber band to stay on. I designed the two plastic ends to provide a base, to steady the pins, and to grip the r