I had some old pants and wanted a new backpack so this seemed like a logical next step. Everything you see here except for the straps came from the pants themselves.
Pants may vary, so unfortunately I can't give a single pattern that will work for every pair. Therefore I recommend continuing only if you're somewhat comfortable improvising with a sewing machine or if you're ok changing route halfway for a drawstring pantsknapsack (not as catchy, I know).
The only thing you'll definitely need are some pants and a needle and thread, but I strongly recommend:
- A seam ripper, rotary cutter, cutting board, and ruler
- A sturdy sewing machine
- Cotton webbing for straps, with two plastic strap adjusters
This can be tedious but also fun and cathartic. Start by ripping the inseam and side seams. you can take out the hem too and remove the waistband and zipper but I'd leave everything else intact for now. Make sure you don't rip out any seams you might want to keep.