This may not look like much, but its a life saver when it came to figuring out how long to cut each of the new rafters.

This is some scrap MDF that we cut the same width of the 2 x 10's (9.5 inches) and we cut the left hand piece to fit at the plate and the right hand piece is cut to match the ridge beam.

We attached one end of a 50 ft steel tape to the one block. We would clamp it in place next to the existing rafter. Take the tape and the other block up the ladder to the peak, measure the distance to the edge of the block. Transfer these measurements and lines a 2 x 10 and presto, you have an exact fit.

This was especially helpful because we did not have to figure out to I measure that from a point to a point and then transfer that to the 2x10. It basically eliminated measurement errors.