# Key Points from DIY Photolithography and Microscopy Discussions

• Participants explored the evolution of photolithography techniques from 1960s contact lithography (200 micrometer features) to proximity printing and step-and-repeat projection systems by 1978, with detailed discussions about film resolution capabilities of various media.

• Several DIY photolithography approaches were shared, including using CD-DVD pickup units for optical mask fabrication, repurposing 35mm slide film for photolithographic masks, and exploring microfilm technology despite its declining availability.

• The group debated cost-effective methods to achieve fine resolution (1-10 micron) features, suggesting laser projection through microscope oculars, repurposing Blu-ray optics, and using Russian LOMO microscope components.

• Microfluidic device fabrication techniques were discussed, including PDMS-based multi-height structures and designing pressure-driven networks using electric circuit analogy, with references to papers on microflow photochemistry.

• A technical debate emerged about microscope automation approaches, contrasting retrofitting existing microscopes (attaching gears to control knobs) versus building custom systems with linear screw actuation for potentially better precision.

• Practical DIY electronics manufacturing capabilities were shared, with one participant reporting achievement of approximately 6 mil trace width when etching 35 micron copper PCBs.

• The discussion highlighted considerations for accessibility in developing regions, questioning whether local machine shops or shipments from China would be more accessible for people in places like India.