This usually elicits a pretty good discussion of how things are built in this day and age opposed to preindustrialized times. We look around the room and see how many things we can identify that were built via mass production, and how many things we can identify that were built by hand or cottage industry, so to speak. I always make one cube before hand to demonstrate what the cube should look like. Team work is the key. Somebody should also be in charge of quality control at the end of the line.
Students can leap frog around if one area gets too slow or too fast.
They'll figure it out. Depending on the age of your students, you can assign tasks or the students can elect foremen or forewomen and let them run the show. I've done this activity with middle and high school students in groups no larger than 20 students. This is a return to cottage industry. You'll get some very cool art projects out of this lesson, and the cubes look great when you hang them with fishing line and a paper clip from light fixtures etc.