John Gill Commentary 1 Samuel 6:11

"and they put the ark of Jehovah upon the cart, and the coffer with the mice of gold and the images of their tumors." — 1 Samuel 6:11 (ASV)

And they laid the ark of the Lord upon the cart
Perhaps the same men that made the cart; however they were the Philistines, yet were not punished for touching it, as Uzzah was, though an Israelite, (2 Samuel 6:6 2 Samuel 6:7)

and the coffer with the mice of gold, and the images of their emerods ;
which coffer was placed in a purse or bag hung at the side of the ark, with the golden mice and emerods in it.