Upgrade your reclaimed boxes and bags by adding sturdy wire handles. Use 2-3 mm...

https://spencerssmartword.quillnesty.com/posts/what-is-a-good-test-load-for-a-new-wire-handled-box-before-i-trust-it

Upgrade your reclaimed boxes and bags by adding sturdy wire handles. Use 2-3 mm galvanized wire for strength and durability. Drill 3-3.5 mm holes to fit the wire snugly without damaging the material