Lengths of steel tubing are cut and bent into curved sections. Joined end to end, they make the circle, octagon or rectangle that most home trampolines take.

The steel gets a zinc skin so it can stand outdoors for years without rusting. In hot-dip galvanizing, cleaned and fluxed steel is lowered into molten zinc, which alloys with the surface.

Legs cut from the same galvanized tube hold the frame off the ground. Sturdier frames use welded joints rather than relying only on bolts and screws.

Polypropylene yarn is woven into a tight, waterproof cloth treated to resist sunlight. This cloth barely stretches, so the force of each landing passes straight out to the springs.

Cut to shape, the fabric has its rim reinforced with heavy stitching and an attachment point for each spring. The first modern trampoline, built in 1936, did the same job with grommets set into a sheet of canvas.

Thick shock-absorbing foam is sealed inside PVC or vinyl covers that will lie over the springs and frame. The enclosure net is made of UV-resistant polyethylene, fine enough that fingers do not catch in it.

Galvanized steel coil springs link each attachment point on the mat to the frame rail and pull the bed taut. A full-size competition trampoline uses around 110 of them.