There’s no such thing as the “perfect crate” for your front carrier but the MT Crate (eMp-Ty, get it?) is pretty close. This 25L box is made of nearly indestructible, black HDPE and is a very handy shape for general urban utility. It will hold a couple small bags or backpacks, or one giant bag of groceries. MT Crate is high enough to support a floppy shopping bag but low enough to stack a big box on top.