Those of you that haven't seen one there is a trap called a B trap that is made with hardware cloth and is fairly easy to build and use. But for fathead minnows or shiners in the bait industry here in MN they use wing or leeds to guide the minnows into the trap.
Fatheads and Shiners will typically follow the shoreline around the pond. The leed is attached to the throat of the trap and staked out into the pond at a right angle to the shoreline. The leed stops the minnows and directs them toward the throat of the trap.
Depending on the Game and Fish Laws in your state you could also build a box trap 2' wide by 2' deep by 4' long close off one end and on the other build a V of hardware cloth vertically with an opening of about 1" in the center. You can use wood for the frame and staples to fasten the hardware cloth to the frame if you need to but you will have to weight it down as wood floats.
If this sounds complicated send me a request by email and I wil draw up plans and send them back.
Bait isn't necessary with the leed and you need only dipnet the minnows out as you need them. BUT check your local laws for size restrictions first.
Barry

What we have done for ourselves alone dies with us; What we have done for others and the world remains and is immortal.