The Insight that most everyone is familiar with (version 4 - see first image) was not designed or ever built with an all built up structure. I have plans...and I believe a set or two of cores (in the attic) for this plane.

There was a version 1 Insight a couple years earlier, which was completely built up (see second image, etc.). Those plans are out on the internet somewhere for free. I can email them to anyone that wants them too.