Sam,
Here is what I built, mostly from scrap, so I probably have about $35 total investment (not counting the crown molding extensions and stop, which I already had).
There are mirrored left and right wings, each about 8' long. It is made from 3/4" pine and 1/4" oak plywood.
The construction is a simple box beam, with one side enlarged to form the fence, big enough to hold my tank-like biesemeyer dual sided stop. On top of each fence is a simple self-stick measuring tape.
On the bottom, one of my few purchased parts is the bracket for the Kapex UG wing (c/o eKat). For a leg, 1 1/4" EMT conduit works perfectly. The leg stays folded when in transport because there is a rare earth magnet glued to the bottom of the wing.
The box beam design makes it light. I have not weighed it, but I can easily pick it up with one hand. It is quit strong. No, I have not given it the "buttocks test" (as championed by certain forum members across the pond), but I'm sure it would hold me.
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Pic 1 - Top view of Kapex end of wing, showing measuring tape.
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Pic 2 - Stop in place, with 12 spacer (needed to use stop on pieces shorter than 11.5")
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Pic 3 - Bottom view of Crown Molding Extension, showing steel plates used to hold the Extension to the wing.
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Pic 4 - Crown Molding Extension removed, showing 5/16" star handles for tool-less attach/remove.
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Pic 5 - End view of wing, showing box beam construction
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Pic 6 - Leg in transport position.
If this interests anyone, I can post a parts list and some dimensions to save you from reinventing the wheel.