I like to make them to keep my hands busy on road trips or while watching movies. They're low-key and relaxing. They're amazing demonstrations of non-Euclidean geometry.
Step 1: Materials
A bit of yarn (the color doesn't matter; it won't show)
Thread. One of the colors of threads will be used a lot. The grey one in the picture was used up. (I often use serger thread for this.) The other colors should look nice together. (I changed my mind on the design of this one, so the threads pictured aren't the ones I used.)
Maybe a flexible tape measure.
Scissors are helpful.
Step 2: Roll a Yarn Ball
Step 3: Roll a Thread Ball
Thread your needle with the thread you have a lot of, but DON'T snip the thread from the spool!
Make a stitch through the knot in the yarn and into the ball. Don't lose your needle in the ball!
Make a few more stitches through the ball using the tail of the thread, until the thread is difficult to pull out of the ball/ the tail of the thread has run out. Put the needle away somewhere safe.
Wrap thread around and around the ball in all directions.
Wrap firmly. Try to use this wrapping to make your ball as spherical as possible.
Keep wrapping until you can't see anything but your wrapping thread.
Leaving a long tail, cut the thread from the spool.
Thread the needle with the tail and make many stitches, all over the surface of the ball, to hold threads in place and to secure the tail.
Pro tip: You can wrap with two colors at once, if you want! You get a gorgeous, deep texture and your ball is covered faster.
Step 4: Mark With Pins
This is the step where you may find a flexible ruler useful. I just do it by eye, but you can be more precise if you want.
Place a first pin directly into the ball.
Place another one directly across the center from the first pin.
Place another pair of pins to create a line across the center that crosses the first line at a right angle. See the first picture.
Repeat to complete a set of three-dimensional right angles.
The ball should now look like the second picture.
One of the pairs of pins will be the poles, and the other two pairs will form an equator. It doesn't matter which is which; they are identical at this point.
Subdivide your "equator", halving each section. See the third picture.
Subdivide each of these sections again. See the fourth picture.
Pro tip: This is not the only way to subdivide your sphere; if you're interested in other non-Euclidean geometric patterns, you can position your pins differently. Here are some examples of different geometric base patterns.
Step 5: Sew Some Guidelines
Cut a long piece of thread.
Without tying a knot, stitch through the ball several times, until the thread is difficult to pull out of the ball.
[use your thread]
Tie off by sewing the tail into the ball just like when you attached it.
Attach a piece of thread.
Wrap a line of this thread around the equator. Wrap, don't stitch!
You can do this several times if you want a thicker line.
With the same piece or a new piece of thread, wrap from pole to pole at each pin on the equator.
Wherever threads cross, make a small stitch to tack your guide threads into place.
I double- and tripple-wrapped my threads to make decorative varying thicknesses.
Step 6: Begin to Stitch a Pattern
Stitch only at corners. Otherwise, wrap.
Repeat on the other side of the sphere.
Step 7: Stitch Around and Around
If you want one color to be thicker, you can repeat it as many times as you want. I stitched the gold thread over three times.
Step 8: Tacking Stitches
I did this only with the gold thread.
Step 9: Voila!
You can give it to a friend, a relative, a child. You can display it. You can make a loop of thread and hang it from a tree or a chandelier. You can make more, in different colors, patterns, sizes.
Update: I have added some pictures of other temari I've made, for inspiration!
(Here are more pictures of the bowl they're in- I made that too!)