Sometimes common industrial items can be turned into common household items with very little modification. A great example of this re-utilization can be seen in the conversion of used heavy-duty coil springs into ergonomic bar stools. The conversion process is simple and straightforward and does not require a whole lot of time to complete.
Locate some heavy-duty truck coil springs from a local junk yard. They should be at least 20 inches tall, but no more than 40 inches tall. The minimum side-to-side width should be about 12 inches. If more than one spring is available, be sure to get enough springs to complete a matching set; coil springs are notoriously hard to match as sets because so many different types and sizes are produced.
Clean each coil spring thoroughly with automotive degreaser. Several attempts will usually be required to get it completely clean. Pay special attention to the coil stubs (where the coil end curves to meet itself). This is where the grease tends to hide the most. Once the coil springs are completely clean and dry, it is time to grind out any imperfections using the bench grinder.
Wearing safety glasses, gently grind the coil surfaces with the bench grinder until all visible imperfections are gone. Rust, scratches and burrs should all be removed. Stand the coils on one end. Do they all sit flat and level? If not, keep grinding. When finished, the coil springs should sit completely flat and level, with no wobble when gently pushed from the side.
Next, apply at least two coats of spray paint to every visible surface of the coil springs. Several light coats of paint usually work best. Once the paint is completely dry, place a bar stool seat onto the top of each coil spring. Make sure they are all as centered as possible and that the stool seats have the same amount of overhang all the way around their perimeters.
Next, working with one spring at a time, fit a conduit clip onto the coil spring at the very top of the spring. Mark with a pencil where the screw holes of the conduit clip contacts the underside of the stool seat. Without moving the stool seat, repeat this process, marking each conduit clip screw hole with a pencil. When finished we will have markings on the underside of each seat top for at least three conduit clips apiece.
Drill small pilot holes in the underside of each stool seat. Attach each stool seat to the coil spring using the conduit clips. Be sure to put one screw in all the pilot holes, and tighten securely. The bar stool spring seat should now sit flat.