I had to remove my SuckIt boot to cut a large experimental piece as I need that extra travel for my job (the Ikea GrowRoom). I had scaled the largest part for some 1/2" commodity ply @Home Depot and I was just short of travel, even with an optimized 45° layout on the bed.
Your local bigbox likely won’t have machinable sheet, but there’s bound to be a local source depending on your location along with tons of online sources. Good luck and post your work as you progress.