Transform your old boxes and bags by adding sturdy wire handles. Use 2-3 mm...

https://avasnewinsights.inkharbory.com/posts/what-drill-bit-makes-clean-holes-in-cardboard-for-wire-handles

Transform your old boxes and bags by adding sturdy wire handles. Use 2-3 mm galvanized wire for strength and drill 3-3.5 mm holes to fit the wire perfectly