A simple and modular stepping stool design, using a single model for the steps and brackets to connect each step.

Printed at 5% based on the amount of weight on the steps. Adjust accordingly.

Onshape file to edit as needed: https://cad.onshape.com/documents/323f02b7406cef62ee29b75c/w/dc386c8d3346878f77ac0e78/e/c842474cde63b4601a258026?renderMode=0&uiState=65f285f4cdc0954490e1e59a