Rockler wood working makes T-channel pieces that look usable; they sell a 4 pack of about 3 inch long T-channels designed to make a cross intersection/four way for T-slots. It's extruded aluminum and anodized - I have no idea what the alloy is, though. Looks great because they are made with two counter sunk holes for screws. The blade size accepted is like 1/4 by 5/8 inch, which is the only problem. The blades (must be at least 2 per wing - is that enough?) would have to be something like 7071, T-6.

The nice part about these are they would be a great, simple bolt-on solution if it would be strong enough. I can get the aluminum in that size all day long.

http://www.rockler.com/product.cfm?O...Select=Details

Anybody know what type aluminum typical extruded is?

The other option is to buy a t-slot cutter:

http://www.rockler.com/product.cfm?page=1572

And build your own receivers using taller blades. As I understand it, wider really doesn't help you on bending moments with beams. The carbide cutters cut aluminum sufficiently well, even though they're really for wood use. You can get mill ends designed for this from Harbor Freight as well.

I've got this same problem working right now.