How to friction fit a knife saya

In the world of Japanese kitchen knife, a saya is the wood sheath that protect the knife from damage. It is desirable to have the saya "friction-fit", namely the knife will hold into place without the need of a pin. It kinda looks cool and expensive.
However, Sometimes (most of the times) a generic saya is larger than the knife and feels kinda loose. In this video tutorial, I will show you how to turn a non-friction fit saya into friction fit.
Tools required:
1. a small wood offcut. Wood needs to be soft, like ho-wood (magnolia) , cedar or pine. You can get it from your woodworking frined, or local timber yard.
2. a chisel, any generic chisel should do the job.
3. a small hammer
4. contact glue / pvc glue
Created by James Zhang, www.knivesandstones.com
Intro (0:00)
Basics explained (0:42)
Prepare the shim (2:00)
Glue together (5:00)
Final thoughts (7:30)