Carlisle, NNock, VWilliams, MAKWhitby, CPChen, JLYAvci, E2025-06-122025-06-122025-05-08IEEE Robotics and Automation Letters, ISSN: 2377-3766 (Print); 2377-3766 (Online), Institute of Electrical and Electronics Engineers, 10(7), 6712-6719. doi: 10.1109/LRA.2025.35683042377-37662377-3766http://hdl.handle.net/10292/19300Optical force-induced assembly is a promising yet scarcely explored approach for developing functional tools and objects at the microscale, with a wide range of potential applications. Our previous work was the first to investigate the manipulation of these assemblies in the XY plane. Here, we expand on these techniques by systematically exploring optical trap manipulation with the addition of Z-axis control. Manipulation of the Z-axis is referred to as axial displacement and is a viable approach for actively manipulating the assembly morphology. Experiments are conducted for the first time to explore and detail the response of the assembly during active 3D trap manipulation, informing the development of an autonomous control algorithm over the 2D area of the assembly during motion. This control presents techniques to increase assembly stability or alter the area of the assembly for tasks such as passing through constrictions. This work aims to develop the control techniques required to create a unique micromanufacturing approach inspired by the Kilobot thousand-robot swarm.© 2025 The Authors. This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/4007 Control Engineering, Mechatronics and Robotics40 Engineering0913 Mechanical Engineering4007 Control engineering, mechatronics and robotics4602 Artificial intelligenceJournal ArticleOpenAccess10.1109/LRA.2025.3568304