After seeing one in a Youtube video, I've been wanting to construct an elevator using wheels clamped onto a "rail"-like guide. I've searched for some kind of how-to or at least a video of someone building something like this, but have come up short every time. In my own attempts, I simply cannot figure out how to build the platform part of the elevator and get the wheels to be around the rail. Do you build the rail first and then start a whole new object and fiddle with the placement until it's right? Do you build the platform/wheels first and then place the rail within the wheels? There doesn't seem to be any tutorial at all on this design, I'm hoping somebody here can point me in the right direction. Thanks!