Blocking hats, mittens, socks, or other three-dimensional pieces of knitting or crochet isn't hard at all. To block a three-dimensional piece of knitting or crochet, you use traditional blocking techniques but with a few adjustments.
Hats: You can steam-block hats while they lie flat, one side at a time. Or find a mixing bowl that’s the right size, wet your hat, and drape it over the upside-down bowl to dry. Styrofoam heads designed to hold wigs are also great for blocking hats. If you’ve made a tam or beret, you can block it over a dinner plate. Be inventive!
Socks and mittens: Use a blocker — wooden sock and mitten-shaped templates that have biscuit-type holes cut out to aid air circulation. They come in various sizes for your different projects. Simply wet down your socks or mittens, gently pull them on over the forms, and let them dry to smooth perfection.
Sweaters worked in the round: You can use wet blocking, spray blocking, or steam blocking. Lay out the completed sweater, arranging it according to the dimensions of your schematic.
If you plan to make most of your sweaters in the round, consider investing in a wooly board, an adjustable wooden frame with arms that you can dress in your wet sweater. After the sweater dries, take it off the frame and — voilà! — your sweater is flat, smooth, and even.