Make a Fake Butt for a Halloween Costume

While you can find fake butts among the novelties at Halloween costume and party stores, it's possible to DIY unisex costume butts in varied shapes and sizes with a sewing project. All the necessary supplies should be easy to find, and the techniques involved are achievable for anyone with basic sewing skills.

Have the costume wearer put on the regular-size pair of tights, bike shorts or shapewea, and then the second, larger pair over the top. Use sewing clips or binder clips to join the waistbands of the two garments together at the side seams or midsides (if the garments are seamless).

With chalk or a disappearing fabric marker, trace a curved line under the natural position of the wearer's butt cheeks onto the outer (larger) garment. Next, trace a vertical line matching the wearer's butt crease.

If you are using tights for your fake butt costume, optionally trace a horizontal line around the wearer's thigh, somewhere above the knees. This is only necessary if you want to cut off the leg parts of the tights; if full-length tights work with your costume, keep them intact.

Carefully remove the double set of garments, keeping them clipped together at the waistband.

If you are using tights for your fake butt costume and want to cut off the legs, do so now, following the traced lines and cutting through both the inner and outer pairs of tights.

Place straight pins through the layers of the inner and outer garments along the traced lines, which should follow the outline of the wearer's buttocks. Place pins down each side and along the curved lines you drew under the butt cheeks. Do not pin the vertical butt crack line at this time.

Thread a sewing machine with thread that matches the garments. Set the machine to sew a medium-length, medium-width zigzag stitch or any other preferred stretch stitch.

Sew along the seams you pinned, back-stitching at the start and end and removing the clips and pins as you sew. Start at the waistband on one side and sew down along the side hip line, along the curved underbuttock lines and back up the other side hip line to the waistband.

Have the wearer put on the fake butt and stuff the butt area with polyester stuffing through the space between the rear waistbands. Pull off a handful of stuffing at a time and continue to stuff it down into the butt area until you have created the size and shape you desire.

Use clips to close up the gap between the two rear waistbands, keeping the stuffing inside. Sew along the waistband to close the gap and enclose the stuffing.

Sew a vertical seam along the line you marked for the butt crack. Try to push the stuffing equally toward each side of the seam while you sew and then squish it back into place after finishing.