Ohhh.. I just had a great idea!
Have someone (your hubby or a local craftsman) use a jig saw or scroll saw to cut out a nice LARGE silhouette of an older sewing machine. Ck out clip art for design etc. Detail paint it up in charming colors and darling detail. Then hang a sign from that.
I can visualize this VERY EASILY. Google "vintage sewing machine clip art......and you'll see some fun examples.