https://www.mcmaster.com/ https://www.mcmaster.com/ Or even https://www.grainger.com/category/fasteners/screws/machine-screws https://www.grainger.com/categor

https://www.mcmaster.com/ https://www.mcmaster.com/ Or even https://www.grainger.com/category/fasteners/screws/machine-screws https://www.grainger.com/category/fasteners/screws/machine-s... Specialty stores? I wouldn't want to do this at scale with Amazon.