pipe layout

[jerky]

first, sorry i posted this in "pro tips and articals" i hit the wrong area to post in.... so here it goes again. i need help making a conical reducer from 2.5" into 2". im trying to lay it out on paper first so i have a template. i got my circumfrence layed out for both diameters, and connected with a distance of 2.5". only thing is when i cut it out and fold it up my ends dont match and arent straight. ill post pics of what im trying to do here in a bit.
the small line is the circumfernce of the 2" pipe and the big is the C of the 2.5.... but like i said, when i fold it in, it isnt straight...... but its a great side view of what i want..