Cut a square bit out of the stock, fit a square bit of wood in larger than your cheekpeice and glue it (with or without dowels) then shape with a rasp, and sand it. (Remember your rasp is going to end up taking more off than you think, because you have to get rid of the rasp marks with sandpaper so stop short a little bit.)
Do what you can with tinting and staining the peice to match. (In my case I now make my own stain using artists oil colours. Burnt Umber will usually get you where you need to go. Put truoil on the stock and then rub in the colour in tiny amounts.)
Use whatever saw you have.
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