Not a very precise motion controlled unit as the high end versions, but nonetheless a very effective one. Here's another Rotisserie Motor based motion controlled Timelapse slider from Vimeo member Derek Mellot. The video shows some fine examples of it's use as well as some of it's build rolling over an aluminum ladder. The motor used spins at 4rpm, but if you're clever, you can find ways to gear that down. I think the other smaller battery powered version with 2rpm posted earlier would suffice. This one by Derek is a large DIY rig, something you shouldn't plan to be traveling with on a plane, but if you've got the time, the space, and lack a budget, it's a great little DIY project. [Thanks Derek]