Traditionally, early stages of the Software Development Life Cycle (SDLC), such as requirement elicitation and analysis are manual, require significant expertise. Creation of purposive machine-processable models is an intellect-intensive task requiring business domain as well as modeling expertise, which is in short supply. To address this, we propose the LLM4Model tool, a configurable, extensible, domain-agnostic solution for automating model authoring with Large Language Models (LLMs) to reduce cognitive load. We demonstrate its effectiveness with two real-world case studies, showing automated authoring of requirements specification model and sharing the results.