Biscornu is a French adjective that means "that which has an irregular form, with projections" or "complicated and bizarre."
To a seamstress or an embroiderer, a biscornu is a tiny eight-sided embroidered pillow that can be used as a pincushion, an holiday ornament, key chain/cell phone decoration, a scissor fob, the centerpiece of a wreath, filled with flower petals or herbs to make a sachet... They're great for anything that you can think to do with a tiny cushion. Biscornus can be cross-stitched, embroidered, hardangered (is that even a word?), anything as long as each side is square and the same size. I've even seen patchwork/quilted biscornus. Biscornus are very popular items for stitchers to exchange; there are many biscornu exchanges arranged online through blogs and forums.
Step 1: A Note About Size
Biscornus can be any size that you desire, only limited by your skill and the materials that you use (the smaller the biscornu, the more difficult it is to turn the corners). I've made biscornus ranging in size from 3/4 of an inch in diameter all the way up to nearly couch cushion size. Most biscornus fit comfortably in the palm of your hand and are made using two pieces of fabric about 4" or 5" wide each. I've chosen to use the slightly-larger-than-average Hallowe'en biscornu that I made for caerbannog for this tutorial because it's easier to see the details.
Step 2: Design
Cross-stitch/embroider/hardanger/quilt two designs. The designs do not have to be identical, but they should be the same size when they are complete. (A biscornu can be made from any size of design so long as both finished pieces of fabric are the same size.)
Step 3: Optional Step: Add Backing Fabric
This step is optional, but I find that it makes your biscornu much sturdier and less likely to pull apart at the seams. Pin a layer of complimentary-coloured cotton or cotton-blend fabric to the back of each side of the biscornu design. If you are using a looser-weave fabric such as Aida or linen, the fabric will show through somewhat and it will keep your stuffing from poking through the weave. This will become your backing fabric.
Step 4: Backstitch a Border
Backstitch a square around the designs. (If you are including Step 2, use the backstitch to attach the backing fabric to the embroidered fabric by passing the needle through both layers. When you're finished backstitching, remove the pins.) This creates your sewing edge for assembling the biscornu.
Step 5: Trim the Edges
The two backstitched squares must be EXACTLY the same size! I can't stress this enough. If the backstitched squares are different sizes, the biscornu will be lopsided (if the discrepancy is small) or plain old won't close properly (if the discrepancy is large). Trim the fabric to about 1cm (just under 1.2") away from the backstitching. For tiny biscornus, this border must be a little smaller or the corners won't fold properly. If you're doing a large biscornu, increase the size of the edge proportionately, but to no more than 5cm (2") or so.
Step 6: Fold the Sides
Along the sides that you will be joining first, fold the edge along the backstitched line towards the back of the embroidery.
Step 7: Pin the Middle of One Side.
If your border has an even number of backstitches, place a pin in the exact middle of one side. If your border has an odd number of backstitches, place a pin in the exact middle plus one stitch.
Step 8: Position Your Pieces of Fabric Side-to-corner
Joining the corner of one side to the middle of the edge of the other side is what creates the shape of a biscornu.
Step 9: Attach Your Thread
Using two strands of embroidery thread, attach the threads from the back of the corner of the first side. You will be able to see your stitches, so make sure that you use a coordinating colour and that you keep your stitches as small and neat as possible.
Step 10: Make Your First Stitch
Make a stitch by passing your threaded needle underneath the backstitch of the previously-marked center of the second square. When assembling a biscornu, the needle should always be passed through the backstitching without ever piercing the fabric. If you haven't been using a blunt-tipped tapestry needle up until this point, then now would be the time to start.
Step 11: Make Your Second Stitch.
Pass the needle through the next backstitch on your first side.
Step 12: Continue Stitching
Continue stitching through the backstitch from the back to the front. Keep the stitches taut to avoid gaps in your attached edges, but not so tight that your thread or fabric buckles.
Step 13: Turn a Corner
When you reach a corner, you may need to stitch more than once through the backstitch, especially if your edges are an odd number of stitches long. If your thread colour is the same as the backstitch colour, this will not show. Corners are the best time to make sure that your edges are still lined up, and to make corrections if necessary. If desired, you can slip a bead onto your thread at this point and stitch it into the corner.
NOTE: The tinier your biscornu and the thicker your fabric, the harder it will be to turn a clean corner. You may have to snip a little of the excess border fabric from the inside of the biscornu to make the corner turn properly.
Step 14: Ornamental Vs. Hidden Seams
If you use thread in a contrasting color with the fabric for backstitches and assembly stitches, you will end up with an ornamental seam. Most biscornus have an ornamental seam, but this isn't a prerequisite. If you want your seam to blend in, use thread that is the same colour as your fabric.
Step 15: You Now Have Eight Sides
As you stitch, you'll notice that you no longer have four sides, but eight.
Step 16: Stop Stitching
Stop stitching when you complete your 6th side.
Step 17: Stuff
Stuff your biscornu, making sure to push stuffing into the corners. Don't stuff it too tightly, or it will be very difficult to sew the last two sides closed. If you want your biscornu to be scented, this is when you would add a sachet to the stuffing -- but make sure that it's a bit off-center, as you will be stitching through the center of the biscornu later.
Step 18: Sew the Last Two Sides Closed
Sew the last two sides closed. Tie off the thread securely, then pass the needle inside the biscornu and out again, snipping the thread close to the biscornu while the thread is taut. The thread end should retreat inside the biscornu, hiding it.
Step 19: Sew on Your Buttons
Sew on your buttons. The thread should go from one button, pass all the way through the center of the biscornu, and then go thorough the other button. Keeping the thread between the buttons very taut is what creates the signature "dent" in the center of a biscornu. Creating this dent is another reason not to stuff your biscornu too firmly -- if there is too much stuffing, it won't dent easily (if at all), and you'll probably break many, many threads trying.
Step 20: All Done
Your biscornu is now complete!