Pastry blender

Pressing the blender down through the fat and flour breaks the fat into small pieces coated with flour, without warming it the way fingertips can. Stop when the mixture looks like coarse crumbs with some pea-size bits of butter left; those bits melt and steam in the oven to make flaky layers.

Two knives or a food processor can do the same job. Blade-style blenders cut through very cold butter more easily than thin wire ones.