For my daughters upcoming first birthday, my dad built her a swing set in our yard. Not your usual kit from a big store, but just some pressure treated lumber and a shovel.
We bought three ten-foot 6x6 pressure treated pieces of lumber. He knocthed them where they will join at the top corners and used two bolts to secure each corner (only attached one until the posts were in their final position)
He dug two holes alittle over 2 1/2 feet deep with a shovel. It was pretty impressive, and it was interesting to find out that our yard is very sandy.
So about 4 hours and 4 pots of tea later, all we had to do was wait for the cement to dry and get some swings to hang.