Give your reclaimed boxes and bags a sturdy upgrade with simple wire handles....

https://wiki-velo.win/index.php/How_Much_Extra_Wire_Do_I_Need_for_Anchoring_Tails_on_Each_End%3F

Give your reclaimed boxes and bags a sturdy upgrade with simple wire handles. Use 2-3 mm galvanized wire—strong enough to hold heavy items but easy to bend. Drill 3-3.5 mm holes to thread the wire through and twist to secure