Measure the area where you want to place your coffee table, to ensure that the space is large enough for a 15 to 18-inch aisle around it. Adjust the size of your coffee table to fit that area. For example, if the available area is 72 inches by 60 inches, it will accommodate a 42-inch to 36-inch-long, 30-inch to 24-inch wide coffee table.
Stack two pieces of 3/16-inch-thick plate steel, cut to your chosen dimensions, on top of each other with all edges flush. Use a soapstone marker to sketch a shape for the table on the plate steel.
Don your welding helmet, gloves and full leathers. Open all shop doors and windows and turn on any exhaust fans. Use a plasma cutter to follow the soapstone lines to make your tabletop and bottom.
Remove your gloves and helmet and don wrap-around eye protection and ear protection. Smooth away all burrs along the edges of each piece of plate steel using a 24-grit grinding wheel on a right-angle grinder, followed by an 80-grit wheel and a flapper wheel, in that order.
Secure one of the 1-inch-diameter steel rods in your bench vise, 4 inches from one end. Heat an 8-inch portion of the rod to cherry red, which is between 1300 and 1400 degrees Fahrenheit, using a propane torch. Grasp the rod just past the heated area with a pair of locking pliers and give it three full twists.
Allow the rod to air-cool to room temperature before proceeding.
Secure the opposite end of the rod in your bench vise and repeat the heating, twisting and air-cooling until you have twisted all four rods at each end.
Don your welding helmet, gloves and full leathers. Position the four rods on one of the plate-steel shapes, spaced as evenly as possible along the length and across the width as possible, so that they point at the ceiling. Weld each rod in place.
Lay the tabletop over the four rods and adjust it until its edges are as close to flush with the table bottom as possible. Weld the tabletop to each rod.
Position the four steel steering casters so that they are as evenly spaced along the length and across the width of the table as possible and weld them in place.
Give the entire table a brushed finish with a wire wheel on a right-angle grinder.