Optical components and systems with dimensions between 10 and 200 mm are discussed with specific examples of testing, simulation, and assembly methods. This size regime, which is conventionally classified with micro-optics, offers attractive possibilities for next-generation micro-optics packaging. However, optics in this regime suffer from few available testing and simulation tools. Several theoretical application examples are described, including a high-index solid immersion lens and a pickup for optical data storage. Challenges and solutions for design and simulation, testing, and assembly of such systems are also discussed.