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

https://devinzort649.timeforchangecounselling.com/2-mm-vs-3-mm-wire-for-diy-handles-which-one-bends-easier

Upgrade your reclaimed boxes and bags by adding sturdy wire handles. Use 2-3 mm galvanized wire for durability and thread it through 3-3.5 mm holes for a snug fit