pulleys

Not sure if it was here or on the old interweb but I once came across a website that simulated motion. You could change stuff around like pulleys and bars and it would show the results. Any ideas? Thanks

I just received a Donna The Dead through eBay. The description said "she is a Halloween prop and although I will pack her well for you, in my experience, these items can fully work one day and partially work the next. Usually with a good swat on the back they work again! I haven't had any...

My box of pulleys seems to have gone rogue - anyone recommend a vendor or store? Building a Flying Crank Ghost.