I have fond memories of playing with a CARDIAC cardboard computer in grade school. They were handed out as something of an experiment, and I'm not sure that it was judged a success, but I loved it.
Well, it turns out that you can order a CARDIAC — but only for a few more days.
Order now: Bell System Memorial- Bell Labs Science Kits – they're going out of business at the end of the month.
Other Bell Science kits available for a few more days which you may recall from the 60s and 70s include “From Sun to Sound”, “Speech Synthesis”, “Energy from the Sun” and “Experiments with Crystals and Light”.