My son had an outdoor wedding and my future daughter-in-law asked if I could make a wedding arbor. The arbor had to be designed to be quick to setup and breakdown since the place where the wedding was going to be held insisted that the arbor not remain on their property overnight. The arbor I designed was held together by a total 20 screws and could be setup or brokedown in 1/2 hour. The arbor is made entirely from cedar to allow it to stand up to the elements and weigh as little as possible. The only real technical challenge was the four semi-circle arches that form the internal bracing and structure of the arbor. The top also presented a challenge in that it had to be designed to interlock to provide cross bracing so the arbor would not rack.
The key to a project like this is making templates. I like to make templates out of 1/2 inch MDF because it is cheap and very stable. Each side of the arbor is 5 feet and the overall height is 8 feet plus the height of the top assembly. The key to this project was the template I made for the semi-circle arches. While the arches are a semi-circle, flat and vertical surfaces had to exist at either side to attach the 4x4 vertical posts.
I wish I had done a better job photographing the process, but hopefully you can get the gist of how this was done.