I was making a 3 string for a VERY small lady, so I tried to make a very low profile neck for her tiny hands. All was going well until I tested the rigidity and discovered I had made a pretty good bow instead.
So what to do? Routed the back of the neck, put a metal rod in it, covered back over with mahogany. Only cost me an extra day and a half on a $250 build, I think I made maybe $8 per hour on that one.