I was able to finish up a couple cold frames last week. I've been working on them bit by bit, as I get a chance and whenever I can stop by the lumberyard or hardware store.
These are pretty standard cold frames - based on Eliot Coleman's "dutch light" design from his very useful book, "Four Season Harvest". I salvaged 2 large double-paned pieces of glass from a set of french doors, then split the panes apart to get 4 glass pieces. I cut a 1/4" groove in 2x2 fir, mitred the corners and framed in the glass. The sides are 2x12 in the back and 2x8 in the front, with a 2x2 runner around the bottom touching the ground. This way, in a couple years, the 2x2 will rot out and can be replaced, instead of the sides degrading.
The frames end up about 28" x 68", and fit over my ~30" beds perfectly. I made two frames this size, and will use my two other glass tops together on one larger cold frame. The green oak leaf lettuce above is already benefiting from the protection - it's in the mid-20's outside.
Oh yeah, and today it started snowing, so good timing!