A rock picker is a machine used on farms and in construction to clear rocks from large swaths of land. The machine is pulled behind a tractor. Steel grates or tines angle slightly into the soil, scooping up loose rocks and tumbling them into a hopper at the rear of the machine. Rock pickers used in large-scale operations are made of the highest quality steel to withstand repeated use for many years. People who want to clear rocks from a small plot of land may also want to use a rock picker to make the job easier. An industrial grade rock picker will probably be too large and too expensive for backyard projects. You can build your own inexpensive rock picker by using heavy-duty metal parts found in scrap yards.
Choose the right materials for the job. If you have small rocks that need to be picked, smaller tines and a smaller hopper are preferable. If you are pulling the rock picker behind you instead of attaching it to an all-terrain vehicle or tractor, a picker made of lighter metal is preferable.
Find a metal hopper that will catch the rocks. The hopper must be durable enough to withstand rocks that will bounce around in it. The front end of an old snow blower, a metal air vent or a metal scoop from a snow pusher make a good hopper.
Purchase rake tines or find a similar metal part with teeth. Rake tines can be found at major home improvement stores or specialty farm equipment stores. Alternatively, use an old barbeque grill or a grate from a fireplace.
Attach the tines or grate to the hopper. The most secure way to attach the tines is to weld them to the hopper.
Attach wheels to the back end of the hopper. Pulling the rock picker will be easier and the front end of the unit will be angled down to the top layer of soil to gather the rocks. The wheels can be from an old lawnmower or you can purchase them new.
Attach a metal or wooden arm to the rock picker. The purpose of the arm is to give you something to grasp so you can pull the picker behind you. The arm can also be attached to an all-terrain vehicle or tractor for larger jobs.