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

https://camilassuperwords.readspirex.com/posts/galvanized-wire-vs-stainless-steel-for-handles-in-a-damp-shed

Upgrade your reclaimed boxes and bags by adding sturdy wire handles. Use 2-3 mm galvanized wire for strength and drill 3-3.5 mm holes to thread the wire through cleanly