Prepare the leather part cut out the shape you want and metal fittings.
In this page, we will use LeatherCraftTools.com's kit product "Leather Keychain Kit <Hawaiian Pattern>".

For the metal fittings, a Double Split Key Ring 25 mm and one set of Long Double Cap Rivets 9 mm are ready for this kit
The leather in the kit has a hole with a diameter of about 3.0 mm for inserting the Rivet.
If you don't use the kit, please make a hole with a Round Hole Punch by your own.

Beveling the edge of the leather with the Edge Tool.
Here, we use LC Super PRO Edge Tool No.01.

Using Burnishing Gum such as Tokonole or TOKO PRO,
smoothing the back side of the leather and edges.

Applying an appropriate amount with a towel or something, evenly rub it into the leather.
When it is becoming a little dry, polish it with the dry part of the towel.
It is more effective to use an Edge Slicker or like that.

Apply an Edge Coat such as LC SP Edge Kote only to the edge surface.
A tool such as a Foam Brush is useful to apply it.

This protects and increases durability of the edge.
After the Edge Coat is completely dry, you can get a brilliant edge by using an Edge Slicker or something.

Prepare the tools to fasten the Rivets.
Here, we use Rivet Setter 9 mm, Multi Size Snap & Rivet Anvil, and Rawhide Mallet.

Pass the Double Split Key Ring through the leather part.

After inserting the Double Cap Rivets into the hole, press lightly with your fingers to temporarily fix them.
Set it on the hole of the Multi Size Snap & Rivet Anvil, that should be matched the size of Double Cap Rivets.

Using the Rivet Setter applied vertically, hit it in with the Mallet little by little to fix the Rivet.

Make sure the Rivet is firmly fixed, then it is completed.
If it is not enough fixed and the Rivet will turn, please hit again a little more.