Q: Can an object like a piston be made to move up a certain amount and to move back down a certain different amount? For example moving up in y 5 and down 3? A: There may be a way to do this with ERC, but I don't know how. You could record the movement as an animated pose, I think that's how I would do it. Also you can incorporate an animated pose into a cr2, let me know if you want details of how to incorporate an animated pose into a cr2. In P7 only, you could use 'dependent parameters' see Ockham's "Tutorial for new 'dependent parameters' in p7": http://www.3dcommune.com/3d/forum.mv?Poser+read+8830039578 ...Or use his Python script linked in his post above.