Oh my God! Remember how you used to WACK the crap out of your wrists when you first tried to use them? But yet, you'd try and try again. And you never failed to injure yourself or someone nearby. I loved those things!
Nowadays, the clackers are for wusses. Instead of string, the balls are on plastic sticks that wack back and forth. No fun without the bruising and pain. Now THAT made it a challenge!
My favorite was a Corgi Chitty Chitty Bang Bang car. Plus, my set of Hot Wheels and Matchbox cars. And that orange track thing you'd clip to a bookshelf or windowsill. Fun stuff!