Create/change mesh with classes?

Is there a way to create a new object/mesh or to change an objects mesh during runtime from a premade class? If so, how so?

What do you mean when you say “from a premade class”?
A Level of Detail system would be fine with for you?

To change yes and it’s easy. To create a new one you need to do some magic (and heavy stuff) with libload, but notice that you have a fixed number of vertex to for mesh (so for e.j. you can create 500 vertex meshes but not 501, you can though create a 1000 vertex mesh and hide 499 vertex, or you can just have a specific mesh that you don’t plan to edit in realtime)