I think the best way is to take the old coverings off the cushions, carefully take apart all the seams and use the pieces as your pattern. I have done this before, and used an old sheet or material as a sample cover to make sure it's going to work okay first before cutting into the expensive material.
I have a friend who has done all the reupholstering on chairs, etc. I think she sure is brave! :) She gets her supplies from an upholstery shop. The people at the upholstery shop even helped her with advice when she had questions.
I made a taco dip for a recent get together and it was almost gone by the time it was my turn in line!! (This isn't "finger food", BUT it's cheap, quick and easy to prepare and a lot of people like it.) I mix a large can of fat free refried beans with a couple tablespoons of taco seasoning and spread in the bottom of a 9 x 13 pan. Then you can add layers with whatever you have--I use fat free sour cream, chopped lettuce, chopped tomatoes, shredded cheese, a bit of salsa if you have it. I also put some chopped onion on it. Then all you need is a bag of tortilla chips and you are done! I hope this helps! ... View related article.