I built a light box out of 1x4s that I found at the local orange h/w store. The finished box measures 36"x8"x4". I includes a low-dB fan that I got from an on-line electrical supply company. Mine is set up for 8 screw-in spiral CF's. I currently use 8x23 W @ 5500K for about 4 wpg with a glass mirror reflector. I'm guessing it acts like most 'cadilac' 3 wpg systems.
The box would easily accomodate AH's DIY kits if you wanted regular CFs. I'd probably go that route if I did it again, just to get the better reflectors.
I've not found it necessary to do anything special for the 'bow' portion of the tank. Since it's usually full of short, foreground plants the light coming from the center reaches it quite adequately.
I'm not sure this helps - it's certainly not a full canopy and isn't especially decorative, but I'd be glad to send photos & further descriptions if you're interested.
My total setup with wood, screw-in bases, fan, bulbs, paint, cord, and wire was:
screws $0 - had a few lying around
paint $3 - 1 can black spraypaint
wire $0 - had it lying around too
lamp cord $2
fan $20 with shipping
mirror $6 from local glass shop
bulbs $30 from topbulb.com (they're down the street - no shipping)
This was cheaper than anything I could buy and seems to work quite well. The other advantage is being able to remove or add bulbs for any desired wpg. I only wish I could find spiral CF's in the 6500-8000K range.