As the garage floor slopes slightly, the shelf was slightly tilted.

This is not a replacement, it's an extension for the already existing one.

Size it around for your needs.

Edit: Info: The OpenSCAD is generated by Gemini Pro 3. So you can easily resize it for your own needs. Instead, to scale it up/down in your slicer.

Outer length is: ca 55mmx55mm. Inner length: 47x47mm (because of rounded corners, slightly smaller than in the drawing) Inner height: 7mm height with rim: 10mm