I decided to try and solder with the sheet mostly vertical. To tie all of the LED's together, I'm using "music wire" (another nice idea that I can't take credit for... this one came from Dave Clausen's LED Cylinder project http://www.dclausen.net/projects/ledcyl/) Music wire is spring steel, so it is nice and straight (and likes to stay that way). I'm using some I got off of eBay. It is K&S Music Wire part number K+S500 (36" long, .025" diameter). It looks like I'll be using around 500 feet of the stuff by the time it is all said and done. Anyway, being steel, I dug out some small neodymim magnets that I had, and found the right combination to get me to the various hieghts I needed to hold the music wire at for soldering. I hold that stack of magents in place with a couple more magnets behind the jig, so they slide around nice and easy. It has worked suprisingly well!