I have a materials question? I use mainly 1/8 birch plywood for most of my projects and for the most part I don’t have an issue but sometimes they bow more that I would like or sit on the machine bed funny causing weird cuts. Is there a wood other than mdf that is more stable than plywood but will not break the bank in the process?
Most ply will do that over time. Try clamping the sheet down. I hold mine down with magnets in each corner.
Do this as a test take a piece of bowed wood… Place concave side use a spray bottle with water and dampen the bowl side, set out in the sun to dry with the convex side up (moist side down) should take the bow out of the wood
I cut my 2440 mm X 100mm sheets done to 200mm wide with bandsaw then stack flat with weight on them
I keep a spray bottle of water handy like @Alex_Krause said to take the bow out of wood. I typically will spray and put some weight on the board cup side down and let it dry. Works great. I also store my thinner wood like @Phillip_Conroy .