: I wanted to get some advice on the best material to build stations
: or forms these days.... plywood or MDF or particle board?
: What thickness do you recommend?

I'd definitely avoid the cheap exterior-grade ('C'??) plywood; I built some forms with that stuff and it wouldn't hold staples consistently- small voids and very soft middle layers.
Better-quality plywood would be my first choice.

The local HD had glued-up solid pine 'shelving' sheets on clearance, and that's what I plan to try on my next project.

I've used MDF - heavy, though. Moving a sheet of that stuff in a small shop is a chore, and I hate the smell and dust.

I was just looking at Ted Moores' book, and notice that his preferences are plywood>particle board>>MDF.