I assembled my XXL but most of the projects I have planned will be aluminum or steel so I wanted a sea of holes base with threaded inserts to hold things tight. The MDF base on my machine had about a .050" difference between the highest point and the lowest point so I decided to add a plywood piece and put the inserts in that. I leveled the entire cutting area on the MDF and then used the XXL to drill 121 mounting holes recessed for t-nuts plus 16 holes to mate the plywood to the MDF. Then I leveled both sides of the plywood. I think it turned out great for my first project (I have no real milling or CNC experience).
Also, I bought a cheap Oneida Vortex vacuum thingy and it worked really well so I thought I’d share that. The vacuum has a HEPA air filter in it but it isn’t anywhere near clogging. I never smelled wood dust or saw any in the garage air. My family is allergic to earth and they never noticed either. Almost all of the material I vacuumed ended up in the vortex can and almost nothing made it into the vacuum. Pretty cool!