I cheated once. Took a coffee can lid and made a hole very near the outside
edge for a pencil.

Put a straight edge at the bottom where the sine wave was to go and rolled
the lid across the straight edge, marking the plywood.

The cutting and sanding were much, much more of a problem than the layout.
I gave up after a few attempts, because even the smallest error is
noticeable be everyone. Just a guess but the wine rack mentioned by OP
might hide small errors in the sine wave due to other objects which would
draw the eye.

Phil


You've had all sorts of answers for how to do this with various computer
programs (or a pocket calculator), but here's another way that doesn't
involve anything but a compass, straightedge and protractor, and you can
lay it out directly on the board:

1.) Draw a horizontal line down the middle of where you want to put the
sine curve, with the ends aligned with where you want the ends of the
curve to go. Call this the "center line"

2.) Make marks (call them "section marks") to divide this line into
equally-spaced sections, one section for each up-and-down-and-back-up of
the sine curve that you want. Mark off divisions of each of the sections
into 16ths.
{snip}