Figure #1
3" Hardwood Sphere : This will be used for the ball of the Flail. It is important that this sphere be as hard as possible to ensure durability of the weapon. You should be able to find one at a craft supply store for a relatively small amount of money.
1.25" Diameter Wooden Dowel at Least 24" Long : This will serve as the shaft of the flail. I would recommend Oak for this, but some may find this to be too expensive.
(2) Threaded Screw Eyes : These should conform to the dimensions shown in figure #1. They can be purchased for under $0.25 each.
Figure #1(146) .25" ID 16 AWG Chainmaille Links : These will form the chain of the flail. The Links will be linked in a box style for maximum density.
Power Drill with 5/64" wood bit
0.5" Wood Nails : You will need approximately 10 of these.
(6-10) Brass Tacks : These will give a nice "finished" look to your flail.
10" x 4.5" Leather Scrap : Makes an excellent grip handle.
2" x 4.5" Leather Scrap : This will minimize damage to the shaft from strikes from the ball.
Stain, Sealer, Paint, Stencils, etc... : Use these to add flourish to your weapon.
Cut your dowel to 24" in length. If you intend to expose your flail to the elements take this opportunity to seal, stain, paint, carve, or otherwise embellish the bare wood components of your flail. Be sure to leave at least one end of the flail shaft free (this is where the screw eyes will be inserted). Once the wood is prepared, drill a 5/64" hole in the ball and the end of the shaft. You should be able to hand twist the screw eyes into these holes.
Using the instructions given for the box chainmaille style construct a chain approximately 7.5" long out of quarter inch inner diameter, 16 gauge links. Connect one end of this chain to the screw eye in the ball and the other end to the screw eye in the shaft. You have now created a simple barebones flail. One of the biggest advantages of this design is it's speed. Once all of the part are collected it takes less than 2 hours to construct!
Figure #2Now you can add a stylish handle to your flail using the larger of the two pieces of leather and the wood nails and brass tacks. Some experimentation will show you the best way of attaching the leather to the shaft to suit your liking. I would also recommend attaching the smaller piece of leather around the shaft at exactly the point where the ball strikes it. this will serve to protect both the shaft and your hands (by giving you a clear mark to keep them below).
It should be noted that the flail is an exceptionally difficult weapon to use effectively and will require a great deal of practice. Safety precautions should be taken when doing so. Happy Flailing!