Pickup trucks are great utility vehicles, able to carry large loads without breaking a sweat. But if you have large items that won't fit in the box, it may make more sense to build a flatbed for your pickup. This is a fairly large project, and should take a few hours to do. The project vehicle in this case is a 1994 Toyota longbed pickup, which doesn't have a bed.
Cut the square tubing using the chop saw into two 1.2 m (4 foot) long sections, and four at 2.3 m (92 inches) long.
Lay the steel out in a square shape, so that the 1.2 m (4 foot) pieces are on top, and two 2.3 m (92 inches) long pieces are on the inside. The overall dimensions of this square shape that you're making is 1.2 m by 2.4 m (4 feet by 8 feet).
Weld the panel using the MIG welder, frequently double-checking for square with the tape measure. Make sure to weld all connecting surfaces on the steel.
Place the other two 2.3 m (92 inches) long sections into the middle of the square shape, and using the tape measure, space them equally throughout the square shape.
Weld the middle bars to the frame using the MIG welder.
Place the flatbed on the rear frame of the truck with the help of an assistant and square the flatbed to the truck frame using the tape measure.
Fabricate mounts to connect the flatbed to the frame using 7.5 cm (3 inch) flat stock steel, bolts and nuts. You'll have to use the drill to drill holes for the bolts to go through in the process. These should be simple, flat mounts.
Weld the mounts to the flatbed using the MIG welder.
Place the 1.2 m by 2.4 m (4 feet by 8 feet) sheet metal panel onto the ground, close to the flatbed. Make sure you have enough room around it to manoeuvre the welder.
Remove the flatbed from the vehicle with the help of an assistant and flip it over onto the sheet metal so that the frame is covering by the sheet-metal tubing. Use the tape measure to ensure that the flatbed is square to the sheet metal so there is no overlap.
Weld the sheet metal to the flatbed with the MIG welder. You want to do short welds, no longer than 1.2 cm (1/2 inch) long, but be sure to skip around the panel so you don't build up heat and warp the metal. You should have at least a few dozen welds on the panel by the time it's done.
Paint the flatbed, top and bottom, with the spray paint.
Flip the flatbed assembly onto the truck and secure it to the frame using the 9 mm (3/8 inch) ratchet and sockets.
These flatbed conversions are also done with wood floors as well, so consider that if you're looking for a lighter option. You can also customise this plan by building removable side panels, ramps, or even a trailer hitch if you so desire. The only limit is your imagination.