I once ordered a few sets of key buttons from Frank Van Valkenburg. I had them specially made for .162 pins and extra wide so I could cut them to the correct width. Frank has sold his key business to Pianotech. You may be able to order from them. If not you will have to resort to making your own. I have a jig that I use on a router table. It plunges a strait cuter of the correct size through 1/4 bass wood and moves back and forth to form the mortise. John Hartman
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