How to Copy a Sweater to Create a Custom Fit Garment.

http://www.ravelry.com/patterns/library/the-anne-meredith-cardigan

Students in my fitting classes are always surprised when they ask me to measure them, because I tell them I don't think it's a good method. Body measurements are very limited in their accuracy and relationship to fit. Ease is critical to good fit and the nature of the fabric being created is critical to how ease works on the body. Measuring tapes can't capture the ease off of a body, however they can capture ease off of an existing garment if the fabric is similar in it's characteristics.
 
If you are a knitter who has made a sweater you are unhappy with that is good news! That sweater is your starting point for the one that is going to work. You will learn more from your failures than you will learn from your success if you take the time for analysis. Many knitters toss the unsatisfactory garment down and move on to the next project, never pausing to take the time to reflect on where we went wrong.
 
If you don't already have a sweater you can work with for this process, borrow one or buy one on sale or at a thrift shop. Too big is usually easier to work with than to small. Choose one in roughly the same weight of fabric that you plan to work with. It doesn't have to be exact but do avoid very fine machine knits.

Put the garment on and make notes on where it fits you and where it doesn't. Use pins to mark things that you would change. Are the shoulders too wide? Put pins where you would like your shoulder to fit. Is the armhole too deep? Pull the shoulder up and pin the shoulder seam to make the armhole depth shorter. Are the sleeves too long? Put a pin where you would like them to end or use a ruler and make a note that an inch or two longer would be better. Continue on correcting anything that you would want to be different.