I have a garage door where the bottom panel rotted out to the point that it is falling apart, mostly its the bottom rail, but the panels don't look great either. I have an idea of how I might rebuild it with 3/8 CDX, a 2x6 for the bottom rail and not sure about the top rail yet. I would use a solid piece of plywood and possibly attach 1x3 pieces to the front and back rather than actually rebuilding true panels jointed into the wood frames.
I already got the hardware removed. Just basically unfastened the torsion springs with the door braced in the up position and then my son and me carefully lowered the door to the down position. I know it's a lot of work but a new garage door is pretty expensive. Plus, my wife will insist on replacing the other one so they match.
I'm basically looking into the feasability of this and tips on how to do it. Has anybody ever rebuilt one of these or are they pretty much just replaced?
Yes, it can be rebuilt, but it is a lot of work. There were a variety of ways wood components were tied together, but the most widely used version is large dowels and glue. Panels should move freely in slots. The hard part will be cutting slots and milling edges. A router works good for that, or take it to a shop that does milling. The new rail will need to fit the old stiles.