How to Make a Wheelbarrow
From Howtopedia - english
BICYCLE wheels make this wheelbar- row easy to roll over a lawn, even with loads up to 300 lb. The front panel slides up for dumping loose material. The body unhooks so the frame can be used alone for carrying pipe or lumber. Angle iron adds strength to 1 1/4" lum- ber to make a rigid, lightweight frame. The wheels turn on standard bike axles bolted between the two angles on each side of frame. At rest, two wood legs braced by 1" strap iron support the outfit. Three sides and a bottom of 1/2" plywood are joined by l/4"-by-2" cleats and rein- forced on the inside coiners with angle iron. Iron strips strengthen and protect the floor. Two 1/2'-by-l" cleats on each side
The front panel in place and serve as guides for sliding it up for dumping. Sides are notched to fit over the cross members of the frame. Eye hooks on each corner lock into screw eyes on the frame to hold the body in place.—W. M. Bosch, Rumson, N. ].
Here's a link to a page on building a simple garden cart / two-wheeled wheel barrow -- uses two bicycle wheels on their own axles, wood, plywood, and iron strips. No welding needed.