This manual describes the development of IMTA Invest, including its main features and functions. The manual is organized into four sections detailing the tool’s design, functionality, and step-by-step instructions for effective use. For future extensions and scaling, feedback on the usability of IMTA Invest’s features and functions was elicited from potential end-users through a participatory, iterative simulation process. This approach ensures that the refinement and future extension of IMTA Invest are user driven, enhancing its practicality, usability, and potential for broader adoption and scaling.