I’m a big fan of getKanban as well (and I’ve got four sets so let me know if you want to go that route!).
I’ve done a homemade/15 minute version of an assembly line using legos. How many cars can we build in five minutes? I bought mini car sets at Target and cut the directions up so there were only six steps. I sort the parts for each step into cups ahead of time.
The first one or two steps are super easy (frame, wheels, etc) but the later ones are small parts and there lots of them (headlights, steering wheel, etc).
I typically have them doing this in front of a larger who is watching and can give feedback at the end. 99% of the time the groups at the front of the line finish quickly with their steps and watch their teammates scramble to catch up. I’ve had ONE group ever where someone went down the line to help. They rarely get any cars all the way to done.
After we talk about how we created a backlog of work for the folks that they couldn’t keep up with, and how that stressed them out. We compare this to dev and test and talk through the cost of finding a defect with a lot of work in progress. We redo the exercise where each person has an index card to signal that they have capacity to take the next car but the person before cant start on the next one until the person down stream takes it (so essentially everyone has a WIP of 1).
I did these at quarterly employee on boarding sessions as a quick way to explain the concepts but if you’ve got four hours I’d pick the getKanban game first