How to steal a pattern

I have spent two hours taking a pattern from a dress I have only worn five times. It was a bit complicated in so far as the bustline didn't have darts but gathers which are hard to measure as they are so small. In the end I used a technique learned from reading 'Threads'. I threaded a hand sewing needle and knotted one end. I then attempted to discover the exact length of the fabric gathered, by using the single thread to go underneath and on top of the gathers. It was difficult and not very successful but better than unpicking my new dress to see how long the gathered section is. To be on the safe side, someone gave me some rather vile stretch fabric so I shall make a toile up first to see what the fit is like. Looking forward to seeing all at the sewing group in early January. Cheers
Jean