These were the shit back in the day. I used to make some of the craziest tracks with these. Hopping the foyer, traversing between my house and my best friend's (we were next door neighbors), looping staircases, replicating traffic jams, hell even circumnavigating our old house with the help of all of my friends (no mean feat at 3500 sqft!). My parents were never terribly happy with that last one, but hey, they bought me the damn things. My inner gear head and my inner physicist loved the kinetic insanity of these old things. Finding a bunch of these in a box made my inner child happy, although this is probably a fraction of the ones I had/have. A couple are crushed, some battered, one munched on by a dog, but each one holds memories galore. Also, a couple windback cars too. Those weren't as fun.
Any other opponauts have fond memories of these things?