The Singercraft guide is a tool that was made by the Singer sewing machine company around mid 20th century so that yarn rugs, and other decorative trims, could be made easily on the home sewing machine.
The Singercraft guide is a flat metal bar, divided into 2 sections by a slot the length of the bar, with a little loop latch to hold the 2 sides together at one end, and with large flattened bulb shaped plastic head on the other end bearing the name and logo of Singer. There is a picture here (I'm not affiliated with this site). The guide also came with a cutter attachment that could be used to cut the yarn loops after they were sewn together. More about this below. There were also extensions available to make a wider yarn loop, however I don't have these.
The way it works: Yarn is wrapped around the flat bar filling the length of the bar, then the bar is set down over a fabric backing and all placed under the presser foot of the sewing machine, lining up the slot in the bar with the needle. You sew along the length of the bar, being careful to keep the needle in the slot, until you reach within 4 or 5 of the last wraps. Then you loosen the little latch, pull the bar towards you, but not all the way out of the last stitches, and make more wraps along the length of the bar. You continue this for the width of the rug you are making. When you get to the other side of the rug, you cut the yarn and begin again, laying the second strand of loops next to, and over the first strand. When the project is finished you now have a thick piled yarn rug. Finish the edges, put a non-slip backing on the rug, and you are done.
My version was done a little different. After making 3 or 4 strands of yarn loops sewn directly to the fabric and breaking 2 needles in the process when the needle drifted off line of the slot on the bar, I figured there had to be a better way to do it. So instead of sewing the strand to the fabric as I made the wrapped strand, I made the strand separately, directly putting the bar under the presser foot, and wrapping and sewing the length that I needed. I then laid that strand tightly next to the previous row on the fabric backing and stitched it down, first one way, then turned it and sewed it back again to make sure all was good and secure. This way worked out better, the bar stayed flat on the sewing machine bed as I stitched, and I could easily keep the needle lined up with the slot as I stitched. I would wrap about 3 inches, stitch, then move the bar back towards me to free up more space for more wraps. I used a heavy cotton yarn for my rug, like the Peaches n Cream brand.
The fabric I used was a denim weight fabric. I hemmed the edges first, but bias tape could also be used on the edges. Then I started laying on and stitching the strands. The finished size will be 16 inches x 30 inches. As you add strands to the backing you have to roll up the excess fabric to fit it under the arm of the sewing machine; if you rug is much bigger that this size, it would be difficult to get it under the arm to stitch the strands to the backing.
The cutter attachment: This is an attachment that fits on the end corner of the bar. It's purpose is to cut the yarn loops after they are sewn together.As you move the bar towards you to make more loops the cutter slices thru the loops, making tufts out of the yarn loops. It's use is optional and can be removed from the bar if necessary.
Other project ideas are making fringe to decorate clothing, pillows, bags, or furniture.
The Singercraft guide shows up on e-bay frequently. But don't pay horrible prices for it; it is not a rare item. As far as I know they aren't made any more, but that still doesn't make them rare. Thousands were made by Singer.
If you are familiar with the craft of hairpin lace, the loom used for that can also be used to make yarn wraps. Or if you are really handy, bend a piece of heavy wire into a big narrow U shape and use that to make your yarn wraps.
Enjoy. Edey