Instead of solid weight why not try a liquid weight system. That will be easy to pull up with pump or other mechanism.
This is an interesting approach. Please see the 3d model of mechanism then explain how liquid weight can be implemented in this system.
Where is the 3D Model? Faiz Ur Rehman
Any link for the model?
Also there will be a pipe that will be attached to both buckets so that an automatic water pump can be activated.
can you please elaborate more?