Ask HN: Where do you buy custom cables?

For many of my home / side projects, a custom cable (custom length, custom pair of connectors) would help immensely. It seems like a simple problem: Select connector A and B, and the length (perhaps shielding and wire type), quantity, and purchase.

Unfortunately, for many cases, digikey, aliexpress, and other go-tos do not have the options I need.