I crocheted some nunchaku, and kept some notes about how I did it. The pattern may take some adjusting for smaller and bigger people, so first, some sizing notes.
Cord connecting nunchaku is more traditional than chain is, and the length should be just long enough that when you lay it across your hand, the nunchaku fall to either side. The length of the sticks on the nunchaku should be long enough that when you hold one stick at the top, the stick protects your forearm. They should be about 1 inch in diameter, and 12 inches long is standard, but I made these for me and I'm short enough that a bit over 11 inches was the right length.
Crocheted Nunchaku Pattern-
Size E or F hook, if you work very tightly, use an F, if you don't work so tightly, use an E.
1 ball black worsted weight yarn, I used Peaches and Creme
small amount worsted weight tan yarn- I used Peaches and Creme
Make a chain with the tan yarn that's long enough to lay across the palm of the person you are making the nunchaku for. I made mine actually too long. So instead of chaining 26 like I did, chain 16, and slip stitch back up the chain to make the cord. Break off yarn leaving ends long enough to stitch in.
Magic ring or chain 2, leave a tail about 4 inches long
Round 1: 6 sc in ring or first chain, slip stitch to join
Round 2: ch 1 (doesn't count as first stitch), 2 sc in each st around, slip stitch to join (12 sts)
Using tail of yarn, stitch the center of the ring to the end of the cord tightly and reinforce, because kids can be rough. You can let the tail hang on the opposite side of the side you stitched the cord to since that will be the inside of the nunchaku and not show.
Round 3-50: Ch 1 (does not count as first stitch), sc in each st around, slip stitch to join.
Now it's time to stuff it, and you've got a few options. You can use a long knitting needle and small bits of stuffing and stuff it that way, but you have to use really small bits and be careful so it doesn't get lumpy. That's what I tried the first time and the shape held up pretty good but there were some lumps, so what I wound up doing was using a piece of plastic canvas that was 11x2 inches, stitched up the long side, and slid into the nunchaku. You could also use milk jug plastic taped into the right shape, or fun foam.
Stuff your nunchaku however you choose, in my case, after I got the plastic canvas stitched, it was as easy as sliding it in.
Round 51- ch 1 (does not count as first stitch) dec 6 times over the 12 stitches, sl st to join, break off, weave the end through the 6 sts, pull tight, knot off and weave the rest of the tail end in.
To work dec- insert hook in first stitch of decrease, yarn over, pull through stitch, insert hook in next stitch, yarn over, and pull through stitch, yarn over, and pull through all the loops on hook.
Repeat for other side of the cord, and stitch the tail ends of the cord into the top of the stick they are on and tie securely. You don't have to weave them in, they will be on the inside of one side of the nunchaku.
These are NOT properly weighted, they are toys. But you can damage knick knacks and such with them. I am so very not responsible for anyone but me behaving irresponsibly.
If you don't crochet, it would be easy to design a knit pair with those dimensions, another option would be to use duct tape and fun foam to make a pair by cutting a sheet of foam in half length wise and taping the cord to one side at the top, rolling the foam into a cylinder, then covering it with tape and repeating on the other side of the cord with the other half sheet of foam.