I don't have close up pictures, but they looked a lot like the Hobie ones in the link at the start of the thread. The beam inserts (or plugs) just had a hole in them and the wings were inserted about a foot into the beams. The material was like a rubbery plastic, so it didn't give the wings a hard edge to rest on.

I just had a Prindle 16 where someone had some wings made in the similar fashion. There wasn't a plug, they just inserted into the end caps. The previous owner had a shop in the Outer Banks make the wings--the shop made outriggers for big fishing boats, so they had the tools to properly bend the wings. They even wlded on fishing pole holders!!