GreatCJ8, I've thought of several ideas:
1. rear vents from a full sized van. Good choice, but too busy, and old, junkyard plastic is brittle - I broker a couple before installing them.
2. Cool hotrod vents. Nice, but too deep. Since I have 2" tube, I have 2 inches of dept available for the fan and the vents. The nice hotrod vents seem to be to small in diameter for the 4 inch fans and too deep.
3. Aluminim roof vents from Home Depot. These are cheap soft aluminum, round vents designed for venting the eaves on houses. They come in a range of sizes. I picke 4" because that's close to the fan diameter. I'll just poke them up through the round hole, them cut some tabs, and fold them down to keep the vent from falling out. They'll swivel in the sheet metal mounting suface allowing the air to be pointed at my head, or at the windsheild do de-fog it. Here's another feable drawing:
http://i7.photobucket.com/albums/y272/Mizedog/vent.jpg
Here's something similar in plastic:
http://www.homedepot.com/prel80/HDU...ID=cccjaddfgdilkhicgelceffdfgidgjj.0&MID=9876
They have louvers in them that can be left alone, or bent to change the angle the air comes out at.
Plus, they will match the aluminum sheet used for the console.
I haven't cut the whole yet. I you have a better idea, please let me know.