A fun project, involving some sawing, cutting, glueing, etc. great for Halloween, or making friends with a marine biologist.
Doesn't take too long, and especially great if you like tedious work.
Stuff you need:
Fabric
Thread (optional - 2 colors)
Felt - 2 colors
Fabric glue
4 wires
Scissors
Sewing machine (optional)

Step 1: Measuring and Cutting the Fabric

First step - measuring the fabric and marking the pattern. I used a little scarf for the pattern. Basically it's 160 cm long, and 12 cm at the widest point in the middle.
For the fabric itself - I think a medium weight fabric would work best. Different colors could also work.

Step 2: Sawing the Scarf

Sew both parts of the scarf on their left side. Do not forget to leave an in-sewed gap for turning the scarf inside-out.
Then, turn the scarf inside-out. Connect each pair of wires together, and also fold their edges inside, to avoid punching through the fabric. Then insert the wires. I used two wires on each side. They would let you shape the edges of your scarf nicely. It's better to sew them in, so that they don't move around inside. You can use either zig-zag or some other wide stitch. I thought that's a great opportunity to use the not so useful star stitch.
Afterwards sew the gap on the right side.
I wanted to add two yellow lines, but only from one side. I used an upper red thread and a lower yellow thread. If your sewing machine is well balanced you'll only see one color on each side.

Step 3: Preparing the Suckers

Choose a felt color that fits your fabric, and cut lots of circles and ellipses. Works best if you first cut all or most of the circles, and then sort them by shape and place on the fabric. Place the biggest pieces in the middle and smaller on the sides. Only when it looks good enough start glueing them to the scarf. There's no way back...
After you glued on the first layer with one color, if you still got some time and energy, add a second layer, at least for the ellipse suckers. It looks much nicer.
I used an old fabric glue I bought some years ago, and it worked very well.