A material library is what designers walk a client through when finalizing finishes. It's a physical collection — fabric swatches, wood samples, stone tiles, paint chips, hardware finishes — assembled for the project so decisions can be made by handling and comparing the actual materials rather than looking at digital images.
Materials behave differently in person than in photographs. Fabrics that look cream on screen might be more yellow in real light. A wood floor sample looks one way in showroom lighting and different in your home's south-facing afternoon light. Paint chips lie depending on adjacent colors. The material library is how decisions get de-risked before they become spec.
For consumers using AI tools, the AI render is a starting point — but the final palette and material decisions should always be validated against physical samples ordered to your home. Ten dollars of paint chips and fabric swatches saves thousands in mistaken finish orders.