I'm looking for some advice around a Scrolling Marquis I'd like to use for a halloween costume using an Arduino Due. My plan is to attach a motor to the bottom "knobs" of each end of a scroll of images (oriented vertically similar to: http://ak.picdn.net/shutterstock/videos/4069165/preview/stock-footage-scroll-of-old-parchment-d-animation-with-alpha-mask.jpg).
My plan is to have two buttons that can be pressed; one would advance the image, one would reverse. I'd either like a single press of the "advance" button to advance an entire image, or have the entire scroll advance as long as the button is pressed in a continuous motion (and have the opposite functionality for reverse). My plan is to have only the motor providing the pulling force to be active when the button was pressed, but as I am unfamiliar with stepper/brushless DC motors I don't know what kind of resistance each motor has when unpowered.
Initially I was looking to use stepper motors to count rotations. When the scrolling was completed both motors would become inactive to reduce power usage. Steppers would also allow me to easily account for the "end of the scroll", and avoid any attempts to scroll in one direction when no more material was available (people unfamiliar with the costume may be pressing these buttons). Concerns around power usage, as well as the need for additional shields/power have made me rethink this situation.
My second thought it to use brushless DC motors to progress or reverse the scroll whenever the button is pressed and held. This would be cheaper from a power standpoint and would not have the "end of scroll" protection. I'm also not sure about the level of speed control this would allow. From what I've read an encoder would improve this, but unfortunately I haven't been able to identify a motor/encoder solution that I'm sure would work for me.
I'd love some input from the community about both which motor option (or maybe even one I haven't thought of) is best, as well as what I should be using for a power source.