Question I need to edit my first mesh

I have some simple assets, a lighthouse and a lamppost. The lighthouse supports two materials so I can light up the windows by changing that material. The lampost has similar looking lights but it doesn't support a second material. I am pretty certain I need to edit the lampost mesh and add a sub-mesh.

Not that I know how to do it but I'd like to try. I played with ProBuilder a bit and while I seem to be able to edit the mesh I don't see an option for adding a sub-mesh. So is there a mesh editor, a tutorial or something that would explain how to add "glass panels" to my lampost?

 

I would recommend KAMGAM ( @_geo__ )'s "Polygon Material Painter" asset.

https://assetstore.unity.com/packages/slug/246853
https://forum.unity.com/threads/polygon-material-painter-sub-mesh-editor.1414542

It takes any existing mesh, creates the sub-meshes automatically as you select polygons and choose materials for them, and it saves the results as a new asset that's easy to use so you don't mess up your originals.

In fact, I would look for one of their package deals so you get their other tool(s) too. Excellent tools for customizing those simple assets that are 95% of what you're hoping for.

 

Sold! Thanks, it sure looks cool.