My wife thought it was a bad idea but...to protect the new sofa we needed some coasters that didn't look like a bargain from a charity shop.
I found a cool designer felt coaster by zigzign a Danish company and thought I could make one.
No offence but I think mine came out a little better.

Although this took some time the end result was worth it (just watch your fingers on the felting needles - be warned, they are very sharp!)

Step 1: The Equipment

You can get squares of coloured felt very reasonably from the net, mine were £4.50 with P+P and had enough material to do 2 nicely sized coasters. Choose your colours and get felting needles (size 40 gauge).

Step 2: Getting Started

Cut the felt squares into 1 cm strips in the various colours you want in the finished coaster.

You will need about 5 sheets of felt cut into strips for each coaster (6 inch by 6 inch sheets). A steel ruler and scalpel are really useful here to ensure even sized strips.

Step 3: Growing the Spirals

Start rolling up a strip of felt as tightly as you can and then secure it using the felting needle (stab the roll of felt all around to secure it - WARNING - watch your fingers, they are very sharp!) As you work your way around continue to roll and stab to secure it.

To build up the pattern make folds and rolls of the felt to create trunk-like knots these are difficult to incorporate but worthwhile to give a less uniform design.

Step 4: Support

After a few cm's in size it started to feel a little unstable so I decided to put some stitches through for good measure. I created a spoke like pattern by stitching from the middle of the outer ring and up through the base and back. I made sure they weren't too tight and these stitches were completely invisible after.

Step 5: Finishing Off

Once the felt is running low I made sure I had some darker strips left over to use as the outer layer and used some superglue to finish the last layer. Careful, superglue was probably not the best choice, my felt was about 60% wool 40% polyester and must have reacted with the polyester because it got very hot!
I was very pleased with the finished coaster. I'm sure there are easier ways to produce these, such as making a roll and slicing sections but I didn't want to buy large amounts of felt since I wasn't sure how successful I would be, and I'm not sure the best way to cut slices without fuzzing the design.