This is an easy to make yarn swift; no measuring, cutting or gluing needed. The only tool needed is pliers. It took me 15 minutes to put together. The materials (coat hangers, duct tape and lazy susan) are things that many of us already have, or can be borrowed or purchased very cheap. The total cost was at least 90% less than the cheapest commercial swift I've seen. Granted it isn't as pretty as a real swift, but functionality was my goal, not aesthetics.

It' s lightweight and easy to set up and take apart. It could be packed in a suitcase easily if you're traveling to a knitter's conference or seminar. The susan isn't modified in any way, so it can go right back in the kitchen when you're done. It works very well with my homemade ball winder.

Step 1: Supplies

two wire coat hangers
duct tape
lazy susan
pliers

Note: "lazy susan" is an Americanism for a rotating tray or carousel. These are commonly available in the kitchenware section of retail stores. Prices start at about $4US and go up depending on size. Mine cost $2, but I bought it several years ago on sale.

Step 2: Preparing the Hangers

Untwist the neck of your hangers and straighten them all the way out. You only need to get the major bends out, it doesn't have to be perfect.

You may or may not need the pliers for this step; depends on how strong you are and how well your hangers are soldered at the twist. Some hangers are made of a more brittle metal, and a piece may break off during this step. Don't worry, there's plenty left for what you need.

Step 3: Shaping the Hangers

Bend your hangers into a shape roughly like the picture. Again, perfection isn't necessary. You will be able to adjust all you want once everything's all finished. The bottom edge is somewhere between 14-16 inches wide (35-41cm).

My lazy susan has a lip around the edge, so I put a slight curve in the bottom. This makes sure that the hanger has some contact with the bottom of the susan when it gets taped down in the next step. If your susan is completely flat, you won't need the curve.

Step 4: Final Assembly

Center one of your hangers across the susan and tape it down with the "arms" sticking upwards.
Now tape the other one down crosswise to the first, so they are perpendicular. Add tape where needed to keep them upright.

You're done!

Step 5: Adjustments

Just like a regular swift, this one is adjustable for the size of your hank. The goal is to have just enough tension to hold the hank securely, but not so much that it stretches the yarn.

To adjust, pull or bend the wires upwards and/or outwards as shown by the arrows. Ideally, you'll want the wires spread just a little bit wider than the diameter of your hank. When you place the hank on, the springiness of the wires will pull it gently outwards keeping it from slipping down.

To use with bigger hanks, bend the arms as shown in the second photo.

Tweaks:
My susan is lightweight plastic. When the yarn hit some resistance, the susan would sometimes slide towards me or even backspin a little bit. I solved that with a couple cans of soup spaced evenly for balance. The extra weight helps control the spin and adds stability.

I haven't had any problems, but if your yarn snags on the ends of the arms, you could try:
slipping a piece of plastic tubing over them (aquarium air tubing, maybe?)
wrapping with masking tape
dipping in plastic dip coating sold for hand tools

If you have an old turntable around, you could tape your swift to it, and have a powered swift for winding hanks.

If I had money to waste, I might use this idea to make a nice looking swift with a wooden susan and heavy copper wire. The wire could be screwed down with some nice looking brackets or metal plates of some sort.