That all sounds so familiar. I was involved with design and low-volume production of a complex optical assembly long before AliExpress. We tried using surplus l

That all sounds so familiar. I was involved with design and low-volume production of a complex optical assembly long before AliExpress. We tried using surplus lenses and prisms, which were practically free compared to new or custom stuff, but the inability to standardize was ultimately more costly in terms of re-engineering, searching for parts, etc. Balancing all that out was an ongoing challenge. I remember finding a factory in India that could make us prisms at a very reasonable price and it was a huge relief. They came in individual handmade pasteboard (cheap frangible cardboard with surface layers of very thin paper) boxes with hand-lettered labels glued on. Old school. I think these will be very appealing for campers, off-grid, emergency and other backup situations when they can hit a somewhat lower price. I understand solar panel costs are dropping, but it isn't always sunny everywhere!