Nicole B has been on a campaign to be sure that everyone - somehow - can indeed manage dividing and marking a Combination 10 mari - and with good reason since there are so many wonderful patterns and possibilities that open up once you can. There are several methods that will accomplish it, and one may kick in with you better than another. There is a photo tutorial using traditional marking strips elsewhere on the site - here Nicole walks you through step by step the likewise traditional method of using mm measurements. (don't flinch, just get a tape meausure and a calculator).

Marking a C-10:

Mark the base into 10 sections (use black and white pins for the poles). Mark the obi with pins, alternating with two colors.

Determine the C-10 division measurement : (circumference ÷ 6) + (1/100 of circumference) = Division Measurement
(For a 30 mm base this would be:   (30 ÷ 6) + (30/100) = 5.3 cm)

Measure this amount down from the North pole at every other division line, using obi pins for marking.  You should move all of one color pins toward the North pole. Measure the same amount down from the South pole, using the remaining obi pins to mark.

Check your measurements.  You should now have the same distance between any two pins.  Adjust if necessary.

Mark the ball.  You are basically going to do a simple 10 divide around each set of opposite pins.  For your first ball, I recommend using a different color thread for each round of marking.

Pick any marking pin and make that your new North pole by replacing the colored pin with your black pole pin, then find the opposite pin and replace your colored pin with your white pole pin.  Now following your marking pins do four full wraps, forming 10 even divisions.   You will go to each colored pin one time. Tack at the new North and South poles and remove those two pins. Pick another set of pins to be the new North and South poles, trade the pole pins for the colored pins and complete another 10 divide around them.  Tack and remove the pole pins.  Continue in this manner until all pins have been used as a pole and removed.  Each new North and South pole set will need fewer rounds to complete a 10 divide (one less on each succeeding set).

Adjust and tack.  To even things out, strive to straighten out the diamonds instead of the pentagons.  Tack all the corners, if desired.