Aluminum?

Hey there, good idea! I just happen to have a piece of that material
about 3/16" thick. Now, which router bits do I want to choose to trim
that out!? If I get it done, I can use an old saw blade to riase up
and make the slot for the blade, then install the finishing blade.

Aluminum scrap is wonderful stuff to use for jigs. If you are buying
any, ask for Architectural rather than structural scrap (they sell cut-
offs by the pound at my local outlet) as it has nice sharp, corner
intersections and appears square. Take your fence with you and you can
test fit bits of channel - I found stuff that perfectly fits my
Craftsman fence - straddling it on three sides - and works to cut on
the ends of a board held vertically. Wear lots of eye protection when
cutting it - $160.00 to get a sliver out of my right eyeball a couple
years back - actually hit my forehead and the perspiration carried it
down into my eye!