I was wandering around YouTube today, looking at videos of various trikes, etc., and I came across a rather interesting trike build.
It's a recumbent tadpole design, using aluminum rectangular section tubing and flat plate, riveted together, and gusseted at all the major angle joints. The builder mentions in his video a weight of 38 lbs.
I found it interesting because the methods of joining the pieces with pop rivets reminded me of similar construction in plans for homebuilt aircraft, and because it appeared to be an entirely weld-free frame.
You can see the video under the title "Raptor Recumbent Trike" at:
A few close-up stills from the video are shown below:
Food for thought for an alternate construction technique to welded steel.
(P.S. As far as I could tell, the builder's choice of the name "Raptor" has nothing to do with the commercially built recumbents marketed under the same name).