I’ve made a lot of laser cut enclosures over the years. I typically make them out of 3mm or 6mm Baltic Birch plywood, and sometimes I even mix the two sizes, which is fun because you need to remember which tabs need 3mm and which need 6mm.
As much as I’ve made a lot of enclosures, I still occasionally screw up, or get things not quite right the first time. Typically I design the entire enclosure in software and then cut things out. If I’m smart I’ll first cut it using cardboard to prototype how it all goes together. Cardboard isn’t always the correct thickness, but it can often get you close enough and reveal flaws in your design that you can correct before you start cutting wood.
One of my recent discoveries is that if your cardboard is too thick you can squish it in the hydraulic press and it’ll stay pretty squished. There’s a little bounce back, but it’ll be thinner than it was originally.