Thin polypropylene boards that roll or flex, sold in sets. They cost very little, weigh almost nothing, and solve a problem that is easy to ignore until it matters.
Two boards, not one. The Food Standards Agency’s advice on raw flour, uncooked dough and raw meat comes back to the same thing: keep raw and ready-to-eat apart, including the surfaces. Away from a kitchen you usually have one surface, no dishwasher and limited water, which makes a second board the cheapest version of separation available. Colour-coded sets make that automatic rather than something you have to remember.
The flex is genuinely useful beyond packing. You can bow the board to tip chopped onion into a pan without a second bowl, which on a small stove is the difference between adding things in time and not.
They are consumable. Once a board is deeply scored it holds onto things that washing does not remove, and at this price it gets replaced rather than scrubbed.
See raw flour for why the flour side of this is not obvious.