That is awesome! Curious... Did you use a CAD program for the catenary curve in the ridge line or did you trace the curvature of a line or chain on poster-board or dod you use some other method?
I got my sewing machine last week on Craig's List for $10. It's 35 years old, in great shape(just time for servicing) and will do most projects I'm told. So, they're out there.