If they have them in your area, the concrete form boards should work
There’s usually 100s on the shelf in my store
https://www.homedepot.com/p/Outdoor-Essentials-MDF-Bender-Board-Common-1-4-in-x-3-3-4-in-x-97-in-Actual-0-25-in-x-3-375-in-x-96-in-487404/202297474