Cardboard is my go-to material to make patterns for fitting my cabinets to the curvy walls of our bus. I picked up two refrigerator boxes on trash day and that heavy cardboard was perfect for making big patterns.
To make a pattern I cut the cardboard to roughly follow the wall to within a half inch or so. To scribe the pattern to the wall I cut a small piece of 1/2" wood block a little shorter than my pencil and taped a pencil to it. Then I held the rough cut pattern against the wall and marked (scribed) the wall profile onto the cardboard by running the wood block against the wall while pressing the pencil against the cardboard. That transfers the wall profile to the cardboard very accurately. Once that was done I'd carefully trim the pattern at the pencil line and re-test the fit.
It's way easier to adjust the fit of a cardboard pattern than to adjust the fit of the cabinet after it's built, but if you do need to adjust your luan panels after they're cut use a belt sander or sandpaper wrapped around a block of wood rather than a saw. It's very difficult to make small curve adjustments with a saw. Sanding takes longer but gives you much greater control.
I was a bit sloppy making my first pattern and was "rewarded" by having to laboriously sand and test fit my big heavy wall cabinet several times to get a good, tight fit. I took more time on the next patterns and those cabinets slid into place nice and tight the first time.