Here is how to make a plough cart, pulled by, say, 4 adults or 8 children. It has 2 wheels and an extension that can slide on the ground. One is standing on it to support weight and to push the blade in the ground by foot, according to the pullers strength. It should not slow the cart too much. The plough on the cart digs the ground about 10cm deep.
Step 1: Main Frame
Construction ideas include the following: The driver should stand more or less in line with the wheels and the plough so the cart doesn't tip over back or forth. The tip of the plough should show to the ground like every plowshare. The 3 footboards should have sufficient space between each other to avoid squeezing fingers and thelike. I cleared the space under the tweeter board axis to avoid collecting and squeezing dirt there from ploughing, which prevents the teeter board from closing properly.
I used square tubes of 30mm edge length. Start welding with flat parts first like the fork of the main frame with the handle. Make the axis bar first continous, add the 2 clamp rings for the teeter board axis, weld the continous axis bar to the main frame and then cut it like it is in da picture. Also make the wheel axis continous first.
As long as things are spot-welded during construction, they can easily be torn apart and rearranged, in case an error occured. Also modular design makes later changes easier.
Step 2: Teeter Board
Find a plough which is small but strong enough or reinforce it like in the picture with a square bar, which is sliced to fit the curvature. Use a round tube that fits on the axis on the main frame, e.g. with 1mm clear space between. Make the socket to hold it all toghether. Keep in mind that the plough tip can pass the end-stop bar in the middle of the main frame. This is the teeter board.
Step 3: Hande Bar
Weld the handle bar. It is screwed for unmounting reasons for a space saving storage. Mount it all together. Leave some holes for possible water to run out, or drill some afterwards.
Step 4: Cord
Make a main rod like the blue one in the picture. The first knot next to the carabiner is a figure-eight loop knot, add a double overhand knot every 20 cm and end like at the beginning. For the handle rod, with the black rope in the picture, use a 10cm piece of a plastic (PE) water-pipe. Then connect the rope ends with a single overhand knot, each rope from opposite sides (or anything), and seperate a part of the loop again with a single overhand knot.
Connect the last with a cow hitch knot on the first rope.
Step 5: Transport
The teeter board has to be tied to the handle bar so it doesn't dig the ground.
The cart doesn't remove roots collected during plouging, so swing out the teeter board from time to time. Have fun!