Help a newbie raise/lower an object (stepper motor spooling/unspooling string)

Sorry, I'm new, but amazed at the possibilities of arduino.

I'd like to lower an object distance x upon trigger by a piezo. Like a knock lock (a given knock pattern as trigger), but instead of unlocking a door, a stepper motor would need to unwind a string from which an object is suspended. Subsequent piezo trigger would raise the object to its starting point. IOW, person stands at piezo, gives the secret knock, and an object from above is lowered to them. They give the knock again (or a different knock if that's easier) to return the object to its original position.

Is this crazy difficult/expensive to pull off?

Ideally, it would fulfill these additional requirements: Distance x=10' Object is 2-3 pounds Piezo is 10' from arduino

Bonus question: what kind of minimum power supply would this require? The location is remote and so I need to accomplish it with batteries/solar.

Call me crazy, or just point me in the right direction for information about what parts would accomplish this. I appreciate whatever guidance you can provide.. Thanks!

Power is going to be your biggest problem, because just an Arduino on its own will use enough power to require quite a substantial solar panel by the time you allow for night time and poor weather conditions and so on. Adding in what sounds like a very substantial power demand from a motor will make the problem much harder - depending how often you need this motor to operate, and where the device will be located, you could be looking at yards of solar panel. On the other hand a deep cycle lead acid battery that you took away and recharged every few weeks would probably be feasible.

A stepper motor is not very efficient and requires power to hold itself in position. You would probably be better off using a geared DC motor, with an encoder to measure how much line has been wound, or some form of limit switch activated by the line.