The box is an enclosure. The top is resting on on the walls and is covered in sound absorbing acoustic foam as are two of the side walls. The other two are removable windows that just slide into place when the top is off.
Now that you've had it for 6 months or so, what do you think of the swm3d kit overall? Fellow Rigidbot owner here.. hopefully this is less fussy! Anything you've upgraded since the initial build?
I think the kit is nice. Since I didn't know what I was doing when I started, it would have been helpful to have a little more detail in the instructions and even more angles of the same picture when describing something. Also, when it came to wiring everything up I was pretty much on my own so I spent a lot of time on the Smoothieware.org website reading how to set that board up. As far as enhancements go, I added the Rockler tracks on my spoiler board for holding things down. Two things I would like to try are to add a laser directly to the spindle mount. With the enclosure I already built, I could easily slide the colored panels into the slots on the purple 3D printed corners of the enclosure for laser protection.