Assuming you already have two pieces of flat metal of roughly the same size with holes about 1/2" drilled in the middle, cut a strap from cloth or leather about 12" to 15" long, and 1" to 5" wide. The length does matter much. The width will depend on how big the hole is, how sturdy the cloth, and how heavy the metal piece. Softer cloth/leather is nicer on your hands, thicker or wider cloth will hold more weight without breaking.
Then cut notches a few inches long on both sides of the strap.
Then fold the strap lengthwise, and cram all four ends through the hole.
Then separate and flatten the four ends in cross.
Then fold one over towards the middle.
Then continue in a circle folding the ends over the previous ones.With the last one, you go over one end, and then under the other. Then pull the ends to tighten the knot into a square.
Pull on the loop to make sure the knot doesn't come through the hole. If it does (the cymbal would have fallen onto your foot) then check the knot to make sure it is square. If a good knot pulls through the hole, then either redo the knot with a penny in the center; or cut a wider strap and/or use thicker cloth or leather.
That's it. Go make some noise.
Drums and Demonstrations