Welcome to the forum.
I haven’t seen a configurator demo per se - but lots of the examples here were very helpful to me when I was learning the basics (and still now) Babylon.js Documentation
If you scroll down to the one labeled “Materials” for example, you can see quickly how to add an object (“mesh”) to the screen and then to change its materials. Click the pencil icon to see the code.
Also check out the example labeled “GUI” - to see how you can add interface controls … that you can then use to control changes to the mesh.
Good luck with the project!