I have CAD so I can sketch out everything beforehand giving me the radius that I would need to make my arc. I plan to lay out the two pieces of MDF that will make up the curve in the driveway (already cut to width to fit) and, using string and a pencil, mark my arc then cut with the jigsaw. The radius on my soffit is about 128 1/16" so I will need a good open laydown space.
You can use this formula to figure out your radius.
radius = H/2 + W^2/8*H
H is the height (or depth in this case) of your arc at the midpoint from the W line
W is the overall width of the arc
Here is a picture.
W should already be set since you have the bottom portions of the light tray figured out. H is basically how far you want the arc to extend out into the room. You will need to offset this dimension some because you will need a straight mounting surface under your ladder structure.
I'm not sure about the rope lights. You'll probably have to ask Damelon about that. I think his actually went above the blocking though. I plan to use LED so I will be running mine above the blocking.
Hopefully that helps you out.Edited by vanice - 10/3/12 at 12:32pm