Place the 20 curves as a supply at the side of the table.
Note: He may not test several curves nor check a chosen curve to see how it fits.
I don't see anything about HOW the curves are placed?
Face up, Face down?
Scattered/haphzard or ordered so all curves are visible?
e.g. does one take a random curve from the supply or can one 'eyeball' the available curves and select the one s/he thinks would best fit the given 'flight plan'?