I just need to print a sample poster for customers to see the actual colour they will be getting.
Then buy them a color book/ colour fan! Honestly, there is absolutely no point in printing a sample for spot colors/ process colors that are based on mixing inks physically. And you don't need samples for conventional composite colors, you do proofs - hardcopy or soft proofs on calibrated screens.
Thanks Mylenium, but maybe I didn't explain myself correctly. I want to print a "poster" of the colour swatch, so when a customer comes in and says "I want green" they can pick the green they want from the swatch poster, and I know my printer will print that exact green on that particular material.