Practice
I’m making a clone of the Rivendell Shopsack for someone in town, so to get the idea of how to assemble the top zipper (as well as fiddly other things like alignment of the inside and outside pockets + reflective trim) I’ve been grinding through my pile of cordura sewing prototype after prototype.
The prototypes are all okay; not great, but okay. I’ll probably fire-sale them on ebay because wide low sacks don’t work very well with cargobikes with low handlebars, but even if I didn’t they’d pay for themselves by being practice and working out some of the more horrific sewing mistakes I’m capable of doing.