Here's my seed starting bench from 2011. The frame is build from a
combination of PVC and wood simply because that's what I happened to
have on hand at the time.
I've got a timer in the back plugged into the wall, connected to power
strips to hook up the lights. Lights are the standard T12 shop lights
from Home Depot which run around $10 per fixture.
The green totes are Rubbermaid. They're the perfect size and strong
enough to allow me to pick up the entire container and move it outside
when I'm hardening the plants.
The planting containers are the large size plastic cups purchased from
Costco. I use a push pin to poke holes around the bottom edge of the
cups (not in the bottom, on the side), fill the cups with soil, place
them in the tote, water the cup to start the wicking process, and then
fill the tote with about an inch of water and leave to set for a day so
the water can move evenly through the soil. From this point I just have
to put water in the tote about twice a week or so to keep it from going
empty and the cups water themselves perfectly - this greatly simplifies
the watering process.
The entire frame I cover with black pastic (it's pulled back to the top
here to allow you to see inside, and on the back side I just staple it
to the wood). The black plastic keeps in heat released from the lights
(all electricity burned by a light either becomes light or heat), and
absorbs excess light turning it into heat which it then radiates most of
back inside the enclosure. I often have in excess of a 20 degree
difference inside and outside the plastic.
If you look close you'll notice the lights are suspended by long chains.
I raise or lower these chains as needed to keep the lights as close as
possible to the plants for maximum light.
I didn't have the bench fully utilized at this time of the year, so you
can see two of my worm bins hiding under the bench on the bottom right.