Howdy Gents! Got a question for you. I'd like to know how I can measure and draw out this piece of metal before I cut it instead of trial and error. Here's the challenge:

Lets say that I have a tube vertically coming out of a flat piece of wood. To make an easy picture lets say it's a drain vent coming out of a flat roof. I'd like to wrap the joint with a piece of metal that has a 45 degree slope to it and wraps all the way around. Like a collar with a slope away from the tube to the roof. I know that from messing around cutting pieces of paper this shape when it's flat looks like a spread out U with the upper ends of the U pointing more outwards then upwards.

It seems like the known measurements would be the distance around the tube, the vertical distance between the ground and the point on the tube where the slope would start, possibly the distance from the tube out to the larger radius the piece would make on the ground, and possibly the distance around that larger radius.

So using those measurements (I think) how can I draw this shape out on a piece of paper?

If I didn't describe this well enough PLEASE let me know. And this is a challenge of course. I bet my wife that race car guys could answer this faster then the bridge and highway engineers she know. Unless of course that bridge and highway engineer is a race car guy. :P

Oh, and no this isn't for a drain cap deal. I have a tube coming out of bulkhead type deal and I'd like to cover up that seem with a wrap around, sloping piece of metal. And ok, I'll admit it, it's for a halloween costume.