But CNC isn't the silver bullet. What I ended up with is 25mm glued wood for frames, 55mm for tops and 15mm plywood plus veneer for facades.
If you use 19mm for frames, you won't have enough strength for hinges, which would inevitably be abused.
If you use 19mm for tops, they will sag and vibrate. The best top I have is actually 55mm IKEA glued oak.
For my project, I believe 19mm is plenty for carcasses - just about every mass-produced kitchen uses 18/19mm chipboard frames, and they can last for decades, outside of abnormal abuse. The main reason for using the same size is easy compatibility with standard doors/fronts together with standard fitment hinges/runners, all of which I'll be purchasing. The tops will be either granite or concrete.
Like, using plywood for verticals is overkill, they don't experience any bending, while 19+19 is 48 so you might as well use glued wood board for example.