Clay Switch is a compact macro for 3ds Max that toggles between Clay and Default Shading modes. It comes from dangtiendung as part of the D95 DESIGN set of scripts, and ships as a small file named clay_switch.mcr.
Once installed, the macro appears under Customize User Interface in the D95 DESIGN category, and it is also listed in the Hotkey Editor as Clay Switch. From either place it can be bound to a key of your choice, and the developer assigns it to the Tab button for quick switching. It handles the single task of moving between the two shading modes.
This is version 1.00, last updated in April 2023. For current licensing and the wider range of D95 DESIGN tools for 3ds Max, the developer's page at d95design.com is the place to look.