I’ve made some progress sewing the seat cover; the front half is done. It looks okay, but the bottom of it is a bit wonky. I’m not completely sure where I mis-measured. Fortunately, it’s smooth and symmetrical from above, so it doesn’t look horrible. It’s good enough — after all, the entire bike will be a “20-footer.” I initially chose red thread because I planned to add a contrasting top stitch around the seams, but I’ve decided to skip that, at least for now. I’m deliberately making it a snap-on cover, so it won’t be hard to recover it at some later date, after I’ve got it up and running. Of course, I might still totally screw up the back half and have to start over.