This is outdated. Take a look at stainless steel shims.
First off I would like to thank the author of http://bt3000.com/ along with the wonderful descriptions of alignment of this great table saw. I especially like the “permanent” solution he has for his shims. He simply glues them into place! It is genius and have done it myself and am very impressed with the ease with which the saw raises and lowers the blade.
I did have to resort to buying a saw for parts to replace my shims since they were mangled beyond the ability to be glued in place. Nowhere was I able to find these: http://www.ereplacementparts.com/shim-p-149355.html
http://bt3000.com/Shim/ is the link for the fix
I have since succeeded in cutting, bending my own shims: https://www.hallcastle.com/2017/04/12/bt3000-shimms-made-from-0-008-steel-shim-stock/