Here is a group of pics to help you put together a small landsailor. All of the materials can be found at your local scrap yard, garage sales, flea marts or can be purchased new. All metals are mild steel or tubing. If you can't find the exact sizes or lengths, just get as close as you can.
Nothing is that critical.
Take a look at the pics for more details. Put some good quality sealed bearings in the wheelbarrow rims. Tools Welder, or access to one. Drill press, portable drill. Bench grinder with wire brush wheel.