Somewhat absorbent chipboard liners for the small trays / dishes under all the kitchen supplies in daily use:

The tray bottom matched the flat surface of the top closely enough to let me lay a curve around the perimeter, with some attention to symmetry:

Then Fire The Laser and it’s done!
For applications where actual symmetry matters, you’d want to lay a quarter of the curve and duplicate it across the midlines. In this case, however, an eyeballometric fit was entirely Close Enough™.
That was easy …
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