This has been nothing short of the excitement I felt when building useless things out of spare parts when I was a child. Granted, this actually has a purpose, and is built out of specific parts, but the excitement captured, for me, was the best part.
BUILD OVERVIEW
I started with the lid, drilling 6 1.5' holes and then filing them out to where the LEDs would be snug in there. I painted the bucket flat black outside and inside with several layers. Then I painted the top half inside white (bottom is dirt). When I tested with light on, there were several spots that needed yet another layer. Overall, I am pleased with the light proofing this method provided, but be prepared to use at least 1 can of flat black just for light proofing Intake has the fan on the outside, with a 4' duct attached at an angle for light proofing. Exhaust fan is attached inside with a 4' adjustable elbow glued into the hole in the side, with a string holding it for support. The carbon filter sits on this elbow perfectly, alas, by coincidence. As of now, I prefer attaching the fan inside rather than the outside, mainly because you can then secure the ducting through the bucket, making it a lot more sturdy. I am planning to build a drip system where vinegar is dripped into a base of baking soda, producing C02 for the babies. This technique is used in grow rooms, so I think it will work quite nicely in a bucket. FUTURE PLANS
PRIMER! Too many paint chips made this job a repaint hassle Install the fans BEFORE the LED strip. Things got in the way of each other. Make much smaller carbon filter Glue gun goes not work on the metal part, not well. Epoxy that part next time. Seriously exploring the idea of a square bucket. I feel that the higher cost will be evened out with the perfect fitting of the fans, vs using a ton of glue/tape/etc making square fans fit to round buckets High power LEDs. As of now, the inter-dimensional portal technology is still in its beta testing phase, but the exploding scoreboard is very likely. 
