I own many items meant to be hung on a wall with a nail or screw, but the spacing between the nail/screw mounting holes is arbitrary. This model is meant to be "universal" by using the multiboard rail system, allowing you to print two pegs and move them freely along the rail to whatever distance you require.

This model is printed in a "folded" manner to strengthen the peg and hold more weight.

Print with 15% infill and 3 perimeters (no supports required) and glue the two halves together.

You can find all the relevant multiboard rail parts here:  https://multibuild.io/