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

https://web-wiki.win/index.php/How_Do_I_Make_Reclaimed_Boxes_Feel_Strong_Enough_to_Trust%3F

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