Use a darning or tapestry needle and yarn in a contrasting color to make duplicate stitches through a hat or mitten, and in 30 minutes it will have a whole new look. This simple technique works only on stockinette stitch, the raised V-shape loops that are common in knit.
Duplicate stitching produces a design that looks integral to the knit. Copy our patterns, or create your own. Each square on graph paper equals one stitch. Work from bottom up, making stitches taut, not tight.
From the back of the mitten or hat, insert a darning needle threaded with same weight yarn as sock through the base of the stitch you're duplicating. Pass needle from right to left behind the stitch directly above.
Insert needle back through the starting point. Repeat for each stitch.