If you launch straight in with a saw you'll risk chip-out, and plywood will only prevent chip-out if it's clamped tight.

The face veneer is a thin layer. The varnish can be brittle. Cut through those 2 layers cleanly and you're away and laughing.

You'll need to cut through the veneer wood grain before using G-Benz's saw and tape to complete the cut.

- Scribe the line of cut using a razor-sharp knife/scalpel and a straight edge
- Go over the cutting line again with the knife guided by the straight edge, cutting through the varnish and well into/through the first layer of veneer
- Use clear tape over the cut line
- Cut out the waste wood with a fine saw on the waste side of the cut (I'd use a coping saw if you're OK using hand tools -- much more precise -- otherwise use a thin blade with as many teeth as possible).
Cheers
John