Here's my shot at a diy cfl fixture/reflector.
2800 x 4 = 11,200 5500k
1600 x 4 = 6,400 2700k
Total lumens = 17,600
It's a VERY snug fit. Got kinda scared when I went to screw in bulbs. I basically used all the same stuff as op except the obvious different arrangement of bulbs. I still have room to install the extra side sockets, but I don't think I'll bother. I just need to add more bulbs beneath the canopy, though canopy penetration is MUCH better I want to eliminate shadows. Thanks for the awesome design! I'm no longer blinded when checking on my plants, no more seeing purple spots after watering.