Some time back I found these instructions. I tried it and they work!
DIY Yarn Swift
By Susan Brockett, eHow Contributor
updated: July 9, 2010
With a few plastic hangers, you can make a yarn swift.
A yarn swift holds skeins of yarn at tension so you can wind the yarn into a ball. A skein, a loose ring of yarn, is one of many ways that yarn is put up" for sale. Because there is not a standard skein size, a swift must accommodate a range of circumferences. You can buy a swift, and some are very expensive. Or with a few common household items, you can make one.
Things You'll Need:
4 x 4 x 4 inch cardboard box
4 plastic hangers
2 9-inch pieces of 1/4-inch wide elastic
12 spring clothes pins
6-inch square piece of gripping shelf liner
Lazy susan, about 7 inches across
Duct or packing tape, optional
1. Assemble the bottom of the box. Arrange the flaps securely on one end. This option allows you to easily dissemble the swift. For a more permanent solution, tape one end shut.
2. Fold the flaps of the top of the box to the inside to add some stability.
3. Stack the plastic hangers on top of each other. Make sure they are all facing the same direction.
4. Tie one piece of elastic around all the hangers, near the bend in the hook. Tie the other piece around one of the narrow, curved ends of all the hangers. Tie the elastic securely to make sure the hangers dont come apart.
5. Hold the stack of hangers with the hook pointing down and rotate the untied ends around the hook.
6. Stuff the hooks into the box, making sure that the cross pieces rest in the corners of the box. Add clothes pins on each side of the hangers.
7. Put the gripping shelf liner on the lazy susan, and put the box on top of the shelf liner.
8. Add clothes pins at the end of each hanger to the yarn skein from slipping down.
9. Drape the skein of yarn around the arms to use the swift. Its triangular or pyramid shape holds skeins of various circumferences. Untie the short pieces of yarn that hold the big ring of yarn together and find the outside end. Attach it to your ball winder and start winding.
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