You can make a Friendship Band in 15 minutes or less, in super fast time.
Here’s how : Kumihimo Kumiloom Braiding Instructions - Video demo.

I came across this video demo from YouTube and tried my hand at it. Looks like a very traditional Japanese Art in simplified form. I succeeded in making a wrist band.
Amazing! It turned out to be a great way to braid a friendship band.

Making A Friendship Band For My Best Friend.

For my first try, I used a small paper plate as the kumiloom.
And it works fine for this simple design.

1. Using a color marker, mark the edge of the paper plate like a compass, North, South, East, and West. There! You have 4 quarters.
2. Then, divide again till you get another 4 segments in each quarter. Altogether you will have 16 segments. fine for this easy to follow video demo.
3. Make a hole in the middle of the paper plate.
4. Next, cut 2cm slits on all the markings around the edge.  The paper kumiloom is ready for use.

I used 2 colors for a start and quite happy with the completed friendship band.

By changing the colors and the number of strings, I would probably get very interesting results. 
You can see that I have added a large focal bead to make it more attractive. Actually, I had trouble finding a large bead with large hole, so I made my own focal bead using 4mm crystal beads. It turned out quite nicely.

So What is Kumihimo?

Interesting answer from Wikipedia :
“Kumihimo is a Japanese form of braid-making. Cords and ribbons are made by interlacing strands.

Kumihimo cord was first created by a form of finger-loop braiding. Later tools such as the Marudai and the Takadai were employed to make more complex braids in shorter time. The most prominent historical use of the cords were by Samurai as both a functional and decorative way to lace their lamellar armor, and that of their horses’ armor (barding). Kumihimo cords are now used as ties on haori jackets and obijimes, which are used for tying on an obi (kimono sash).”.