A poncho is one of the world's simplest sewing projects, largely because it requires almost no sewing at all. It's also the perfect cover-up for spring, when the weather becomes too warm for heavy coats and too chilly for just sweaters. We're all familiar with the South American ponchos that tend to be rectangular blankets with a slit for the neck.

This one is a little more sophisticated, and fits better too. It's made with a fold at the shoulder line just like the blanket ponchos, but the sides are cut in a curve close to the body, making the sleeves look something like angel wings.

I suggest that you sketch out your poncho measurements on wrapping paper and get the curves perfected before cutting out your fabric. My poncho began as a folded rectangle measuring 56 inches from arm to arm, and 38 inches form the fold at the shoulder to the bottom edge. On each side I drew a line, starting 8 inches below the fold and gently curving in toward the center, 12 inches from the side edge. That left me with a hemline measuring 32 inches across and lots less bulk on either side to get in the way.

Almost any heavy, blanket-weight fabric will do, but a real blanket is even better. Pendleton, for example, makes some marvelous ones with authentic American Indian designs.

Simply cut out the shape and finish all the edges and neckline slit with a row of machine stitching one-fourth inch away from the raw edge. Add a creative touch by working a row of blanket stitch by hand in matching or contrasting colored knitting wool all around the edges. Fasten under the arm with a button and buttonhole.

A handy kangaroo pocket can be made from leftover fabric, edged with blanket stitch and sewn on the front of the poncho. However, since this sort of pouch pocket is likely to take a beating, I suggest you "clean-finish" it first, using taffeta or China silk for the lining. To clean-finish, place the pocket and matching lining section right sides together, and machine-stitch all around, leaving about 6 inches open at the bottom. Trim the seam, clip the curves, and pull through to the right side from the opening. t

Blanket-stitch around this finished pocket and attach the top sides and bottom to the poncho with a tight, invisible slip stitch. The curved part stays open to form a deep pocket that can serve as a mini-muff on cool spring evenings.

Q. I am eager to crochet a "ribbon" sweater. I have been told that seam binding is used, but I cannot find directions. I have also been told I cannot crochet with ribbon. Please send me any directions available.

A. Of course you can crochet with ribbon! Or knit with it, for that matter. In fact, ribbon sweaters are cropping up all over in the very best boutiques at very high prices. I have seen sweaters knit and crocheted from bias-cut strips of fabric in solid colors or pretty calicos. You can even buy these fabric strips pre-cut and wound in balls called "Ragtime" made by Knitting Fever of Cedarhurst, N.Y.

Take any simple crochet or knit pattern that uses a large hook or needle and use ribbon instead of the heavyweight knitting yarn called for. Crochet or knit just as you would with yarn, letting the ribbon curve back on itself as it slips through your fingers. Of course, as all expert knitters and crocheters know, your gauge (the number of stitches in the inch) is all-important and must agree with your pattern instructions whether you use ribbon, bias-cut fabric or regular knitting wool.