These free lawn swing plans are nice and detailed. The hardware needed is very limited as the hinging of the swing is handled with off the shelf hardware and lumber rather than an expensive swing hinge.
"Natural" Playgrounds: a natural playground, natural playscape, green playground or natural play environment is an area where kids can play with natural elements such as sand, water, wood and living plants.
Keystone Glider with 40" seats and green top "Lawn Swings designs and builds swings, gliders and arbors. All items are hand built in family's workshop. They use treated yellow pine and stainless steel screws to withstand the weather. Their Arbors are made from interchangeable panels which give you the ability to customize and beautify your gardens and walkways."