IPA: /ˈmɒd.ələr/
KK: /ˈmɒd.əl.ər/
A person who creates or designs models, often for art, architecture, or engineering.
The modeller presented a detailed scale model of the new building.
Modeller → It is formed from "model" (from Old French *model*, meaning a representation or example) and "-er" (meaning a person who). A modeller is a person who creates a representation or example of something.
Think of someone who creates a 'model' — that's what a modeller does, they make representations or examples.