Here are some pics of my dust shoe. The fixed piece is cut from 2x6 stock, and is attached to the router with a hose clamp. The bottom of this piece projects ~1" below the bottom of the router, about as far as the rotor lock key way lies. The removable part lies below the fixed piece as well as under the router. The hole for the tool is as small as the nut will allow.
Cooling air from the router is mostly on the outer diameter of the router, not near the bit itself. This cooling air gets deflected outwards, parallel but above the work to minimize chip-storms. I know there is some debate about doing this, but it seemed that since this cooling air is not helping the vacuum do its job, why not get rid of it?
The skirt is 0.25" thick neoprene picked up at a local textile store, and it staples well using T50's. Two lenghts of skirt for different tool lengths; colour coded by my daughter. The lower piece of the shoe is aligned using 2 1/4"-20 studs projecting downwards from the fixed piece, and it is held in place with three strong magnets scavenged from hard-disk drives (used to move the read/write heads). On each lower piece there are bolts heads flush to the top surface that line up with these magnets and make for quick changes but solid mounts.
BTW : The reason the fixed piece is attched using a hose clamp is because this shoe projects out far enough to interfere with the 'elephant feet' that support my rails. Depending which axis is causing problems, the shoe can be rotated in 30 seconds.