Share 'Connecting 2x4 to a 2x4 using clamps'

Hi, I am new here and have a few questions. We are building an outdoor patio set using this plan and are only building armless chairs, not the corner piece. http://www.morelikehome.net/2011/06/our-new-outdoor-sectional.html As you can see the seat top are a lot of 2x4's with 1/2" spacing between them.  We have two different kinds of clamps, neither of which makes it easy to connect the corners…