How to creat a IR pen

Today in class, we got all the materials for the IR pen, which are 1 momentary switch, 1 wire to connect the pen with the battery pack, 1 spring made of coil, AAA bateries, and a sharpy pen. During the class, we made a how to video, about how to creat a IR pen for the multi-touch whiteboard. We recorded the video in 3 steps, the introduction, showing the materials that we need for this project, and taking the guts out of the pen and making a hole in it. It was harder than what I thought to make a video, because my friend was keep laughing when he recorded me. By the next class, we will have to continue recording the video. (Their are 3 more steps left.) It is harder than what I thought, to get the sharpy pens. I'll go to a papeleria and try to find one. Today I bought 2 wrong pens and brought 1 wrong pen.