Purchase six to 16 wooden crates. Whatever number you decide to use, it should be an even number. They can be the crates that carry fruit or other products or vintage wooden crates. They should be identical in color, size and shape.
Stack your crates on top of each other, creating a square or rectangle with the bottom of each create pressed against the wall, creating an open cubby for shoes and other items. Decide which wall you want to mount them to in your mudroom and how low or high you want them to be. For example, they can start at floor level, like a shelf, or suspend higher, making them closer to eye level.
Press the bottom of each crate against the wall, holding it in place with one hand, pressed against the inside. Nail each crate to the wall, hammering a nail in to the four corners of each. Continue in this manner until you've nailed all the cubbies into the wall in a square or rectangular formation.