Get a metal 55 gallon drum. Go to your local junkyard, or look around local warehouses or garages for any drums they may be throwing away. Make sure the drum is fairly clean and is not coated with oil or paint. Remember that you can burn off some of the residue when you light the grill for the first time, but you don't want anything flammable or poisonous inside the drum.
Put on your welding goggle and gloves. Weld the top of the 55 gallon to the main part of the drum.
Set the drum on the ground lengthwise. Draw a line around the entire length of the drum so that 1/4 of the drum is on top, and 3/4 of the drum is below the line.
Cut along the marker line with your reciprocating saw so that you can remove the top 1/4 of the drum.
Smooth or sand the rough edges of the line you cut with your grinder. Make sure there are no jagged edges anywhere along the cut.
Make support bars for the grill surface or grate. Place your tape measure inside the bottom section of the drum. Measure the diameter (length from front to back) of the drum at its widest point. Cut four metal support bars to the length with your reciprocating saw. Install the bars into the bottom portion of the drum and space them out equally. Weld the bars into place a little more than halfway from the bottom of the drum.
Measure the length and width of the area inside the drum to get your grill surface dimensions. Purchase grate type material (such as fencing or even heavy chicken wire) to make the grill surface. Cut the material to the proper size with the saw. Place the grill surface material inside the drum, on top of the support bars.
Place the top portion of the drum onto the bottom portion. Place two or three sets of hinges on the backside. Drill out the holes. Attach the hinges with a nut-driver and socket wrench.
Place a handle on the front portion of the grill. Drill out the holes. Attach the handle with your socket wrench and nut-driver.
Drill four holes in the top of the lid to act as vents. Try to make the holes about 1/2 inch to 1 inch in diameter.
Lift the drum onto a metal trailer, or onto a metal cart with wheels. Weld the drum to the trailer or cart so it cannot roll off.