Give your reclaimed boxes and bags a sturdy upgrade by adding wire handles. Use...

https://wiki-coast.win/index.php/How_Do_I_Smooth_Sharp_Wire_Ends_After_Cutting%3F

Give your reclaimed boxes and bags a sturdy upgrade by adding wire handles. Use 2-3 mm galvanized wire for strength and thread it through 3-3.5 mm holes drilled near the edges