I basically clicked them all haha. I have a full face mask, got a half face and paper ones as well, try to wear them but don't wear them all the time every time but have gotten better. Got a dc and shop vac I try to use every time I can, my miter saw and lathe are the two things that make a lot of dust and I don't have anything on them which sucks. I've got two makeshift air filters made from box fans and filters, probably not as good as units you can buy but they do work. The paper masks def aren't the best but they're better than nothing.
I bought the shapeoko 2 a couple years ago having plans to use it a bunch with my work. Wasn't the best machine and i wasn't the best at using the software so it collected dust then I sold it. What frank does with the cnc is really cool, of course all of his work before his cnc was amazing so not much of a game changer for him I don't think. One of my buddies was just a turner and started to get into flat work. Then he bought a cnc and now he's a manufacturer not a woodworker. He posts and sells the stuff on facebook and I see people say how talented he is, I find myself cussing at my computer because of stupid people on facebook haha, mdf signs cut out by a machine and painted isn't talent. A lot of the youtube woodworkers got cnc machines but it seemed to be a fad for them, and a lot of them don't seem to have any interest in them as well. So there are guys who can find a regular use and guys who think they will but don't, so if you have tons of things you think you'd use it for, go for it.
I would make it from solid wood using 3/4 thickness and use a 45 degree miter down the sides to "wrap" the face grain all the way to the side. I would add a couple of ribs to the back for stability. What I am describing is a torsion box with an open back (assuming your headboard will be against he wall, this has plenty of strength)
That will allow you to choose from more varieties of wood when compared to 2" solid wood construction, and it will be lighter, less expensive, and eliminate the exposed end grain
@TIODS is right about facial hair. You need a tight seal against your skin to ensure all air passes through the filter.
I owned a company (sold it in 2014) that performed asbestos abatement (safe removal) so please trust me that I know something about dangerous dust and protecting people. It's the very finest dust particles that are the most dangerous - you need real HEPA filter that captures at least 99.97% of particles 0.3 micron and larger. In my opinion any other filter is a waste of money because it is basically useless.
My employees used the North series of respirators with P100 HEPA filters and I use the half-face version of that same respirator in my shop - even with my Oneida V-3000, Festool CT-26 and HEPA air filter/cleaner. My health isn't worth risking - especially when excellent protection (in the form of a respirator) is so simple.