An example of a simple machine is a pulley.
Fallside, D.C. & Just, M.A. (in press) understanding the kinematics of a simple machine.
This simple machine doesn't contain weight plates or pulleys; instead it uses your own weight as resistance to tone your hams and glutes.
If you're looking for a simple machine for a child learning to sew or to perform basic sewing, you might want to consider a vintage Singer.