Determine the appropriate size of the sofa for the room where it will be going. If you already have a sofa that is the correct size and shape for the room, you can use that as a guide. If you do not have a sofa to use as a template, you can use Kraft paper to cut out an appropriate size and shape of the sofa and tape it to the floor with painter's tape. This is a trick that many professional interior designers use, particularly in small or difficult spaces where it is hard to determine the correct sofa type and size without a visual reference.
Contact a local furniture builder about making the sofa. Explain the dimensions of the sofa, the style of the room and what your budget is. Ask the builder to make a preliminary sketch of the sofa and to give you an estimate for the project. Consulting several builders in your area to get quotes for the project is recommended.
Find a local furniture upholsterer. Show the upholsterer the sketch given to you by the furniture builder to get a price on the project. You will need to find out how much upholstery material will be needed. This should be included in the quote given to you by the upholsterer.
Choose a color scheme for the sofa. You can use a paint chart to determine the range of colors that could work for upholstery fabric. Doing this beforehand will save you a lot of time when you begin to look at upholstery materials for the sofa.
Visit a local fabric store to choose upholstery material for your sofa. Explain your color scheme, style and budget to the attendant. Upholstery material can range from several dollars per yard to hundreds of dollars per yard. Be specific about your budget to avoid wasting time looking at fabric that is too expensive or does not meet your quality standards.
Schedule a furniture mover to pick up the sofa from the upholstery shop when completed if you cannot do it yourself. Some upholstery shops will deliver furniture for a small charge or as a complimentary service to customers, though some do not. Ask your upholsterer before starting the project.