1 5/8” channel with 4” aluminum tube and some 5mill thick shims to make it snug. 1/16” shims could be used with a more standard 3.5” diameter router (porter cable, Milwaukee etc)
Here is my question what is best way to keep the router in place? I was originally going to cut a slit and use a t bolt hose clamp. But now I’m thinking a simple tapped hole with thumb set screw.
Original plan was to 3D print the router clamp but getting it made out of metal is only a few dollars more and makes more sense with a name like metal Maslow.