In this video, at 17:31 they show two of them, attached to each other, bit don't really talk about it:
There is another example here, at 6:55, described as "a simple stepper":
And again at 15:26,
I've tried to make a couple other ones, in particular a ball pump and a lift arm module, based on instructions I found. And they sort of work, with lots of hand holding. For about 2 minutes, then they jam, or fall apart. I want to make one simple one, that just works, to gain a little confidence. Then, as I better understand whats going on, i plan to re-visit my earlier attempts and fix them.
Edit: Looking closer at Maico's site, I see two modules that are very close to what I was thinking of! http://greatballcontraption.nl/bi/eerste-kleine-mini.pdf and http://greatballcontraption.nl/bi/transparante-mini.pdf. I'll try those! Thanks!