These are Peter Billam's suggestions for making the most personal and the prettiest juggling balls in the universe. The dodecahedral pattern is how balls were made in ancient Greece. Modern footballs are made in a similar way, though they have more faces and are reinforced with a bladder inside.
These balls as I make them are stuffed with linseed and don't bounce; I'm not sure how well they would stand up to being used in a bat-and-ball game as I've never tried - in my opinion they're far too beautiful to be hit around in the dirt. They are vulnerable to sharp objects, and to moisture. They can also get scuffed by rough surfaces. If filled tightly, they have a stage-ball feel, nothing like a bean-bag.
The patterns are written in Postscript. I find Postscript a very useful language, and write a lot of it:
You are welcome to redistribute these patterns and instructions in any way you choose, and to use them to make juggling balls to sell if you wish :-)
Leather is available tanned in all sorts of bright colours, or you can use your old boot-leather for an extra-personal set. My favourite colours are red, orange, yellow, green, blue and violet, together with white, black and various shades of brown.
Use leather about 1 mm - 2 mm in thickness; every face in a ball should be from leather with the same stiffness. It looks great to have different colours of leather, so the different leathers have to be selected to have the same thickness and flexibility. The patterns with few faces, like the Tetrahedra and especially the Two-piece balls, need some stretchability to get the right shape, and are especially fussy about the leather of the different faces being matched.
Two-piece balls (like a tennis ball or baseball) need two contrasting colours.
Tetrahedral (4-sided) balls look best with four different colours. Because each face is so large, the spectator quite often gets the impression that the ball only has one colour, so these can give more the impression of a ball that changes colour, rather than just a multi-coloured ball.
Cubic (6-sided) balls are at their best with three colours, arranged so that no side has a neighbour of the same colour.
Octahedral (8-sided) balls are great with two contrasting colours in a chequered pattern.
Dodecahedral (12-sided) balls are interesting. They look very good with four different colours arranged so that no side has a neighbour of the same colour. This would illustrate the Four-Colour theorem except that the Four-Colour theorem applies to maps on a plane rather than maps on a sphere; still, it refers to it. The four-colour patterns have chirality, though it is not obvious at first glance; it can be seen by pairing the four colours into two groups of two.
But there are also some interesting dodecahedral two-colour patterns:
With three colours, three separate two-fold reflectional symmetries arise if each colour is arranged in two opposite patches of two faces each.
Dodecahedral balls also have an excellent six-colour pattern; the two faces of each colour are placed opposite each other, and whichever angle the ball is viewed from, all six colours are visible.
Icosahedral (20-sided) balls look best with five different colours arranged so that no face even touches vertices with a face of the same colour.
These patterns have the faces bulged out slightly, so that the corners meet flat, and the ball comes out with as spherical a shape as possible. Even the "cube", with just six faces, comes out spherical enough for contact juggling - the diameter is constant within +/- 1.5 mm. Only the "tetrahedron", with just four faces, is too lumpy for contact juggling; it has a shape a bit like an egg with four ends. It's a smooth shape, it feels good in the hand, and is very jugglable - but it's not spherical. The "two-piece" pattern is fussy about its leather; if the stretchability is exactly right it can be very smooth and round.
Save the pattern to disc (Shift-Click in Netscape) and print it out at will.
Then, glue the pattern to the back of the leather with a light glue (like a glue-stick for paper), and dry pressed flat. Pierce the holes with an awl accurately in the centre of each dot. For each face, cut out with sharp heavy scissors down the centre of the line, and peel the paper away from the leather.
The Two-piece pattern has some holes marked with little circles; these align the two pieces when sewing, so put the first thread through two alignment holes before peeling off the paper.
Sew using waxed thread and two needles. The seams will end up hidden inside the ball, but you can start inside-out until the last couple of faces. Stitch in lengths of one, two, or three seams and then tie off with a surgeon's knot (see picture). Always pull tight as you go; keep everything evenly tight, and check the seam is straight. If the seam crinkles up when you pull tight, jiggle it back straight again before continuing.
With a couple of faces to go, turn the ball right-side-out while you still can, and stitch everything up except for the very last seam by folding the ball so that the seam you are working on sticks out. Pull tight as you go. If you fold the ball right, you shouldn't be forced to pull tight with one thread over the end of a thumb held inside the ball.
The last seam is more complicated because the filling process takes place during it, and because it has to be pulled tight and tied off from outside.
Use one thread as usual, but make it a much longer thread. Start sewing normally, pulling tight as you go, until the remaining lips of unsewn leather are just big enough to admit the small plastic funnel; then pre-thread the remaining holes loose, with a lot of slack in the loops between the lips. This leaves just two ends exposed and ready to pull on later.
Insert a small plastic funnel between the loops and through the lips, and pour the filling in. Ram the last bit in with the blunt end of a pencil with two blunt ends. Ram lots in - the leather should be stretched, inflated.
Then pull the thread ends till the loops have no slack, remove the funnel and keep pulling. When the last seam is tight and looks the same as the other seams, tie off the ends in a reef knot, and poke the knots and the stray ends inside the ball to make them as invisible as possible.
For filling, birdseed (unhulled) millet is commonly used, though the seeds slowly crumble making the ball gradually softer; also, some people are allergic to millet. Sesame seeds are longer-lasting, but linseed is the best of the seeds. Crushed walnut shell is still more hard-wearing and moisture-resistant; it is sold in pet stores as "bedding" for birds and hamsters, and is also used in place of sand as an abrasive for sand-blasting. Rice is too heavy and is not durable. Plastic pellets are completely moisture-resistant, but I prefer juggling with the feel of the natural materials.
Your first few balls will take you about a day each, it speeds up after that.