A Cartesian product takes two lists and produces every possible combination of one item from each. Ten modifiers and forty product names give four hundred phrases, generated exhaustively rather than remembered.
Why generate rather than brainstorm
Human brainstorming is patchy. You will produce cheap running shoes and best running shoes and forget running shoes near me entirely — not because it is a bad term, but because attention ran out. Exhaustive generation has no attention to run out of.
The obvious use
Modifiers crossed with products. Cities crossed with services. Brands crossed with comparison words. Any two dimensions where every combination is potentially a real search.
The necessary second step
Most generated combinations are nonsense. Generation is cheap; validation is the work. Push the output through a volume checker and keep only the phrases people actually search for.
Try it: Cartesian Product (Keyword Combiner) on SeoWolf's Notepad.