No cover so there's potentially some additional ambient cooling benefit (it also looks cool with the danger sticker visible). At very least without the cover it's less to print.
Added a duct to better direct the air flow over and around the heat sink. The line lasers are aligned perpendicular to the work surface to avoid spraying even low power laser radiation around unnecessarily.
Rotate 180 degrees and it'll print just fine without supports. In PLA at 0.2mm layer, 100% infill it took about 4 hours. That's probably massive overkill, 20% to 50% infill should be fine.
(2) M3x20 to mount the laser
(4) #6-32x3/4 to mount the cooling fan
(2) #6-32x3/4 to mount the tool block
(2) line lasers from Adafruit
The line lasers are a press fit and require no hardware. If it's too tight, use a straight screw driver and gently pry the split apart a little for assembly and fine alignment.
Fit the 2.8W laser last.
There's no provision for squaring the main laser to the work surface, I'm relying entirely on the accuracy of the printer in this design. If it becomes necessary later the circular mounting holes could easily be made oblong to allow for adjustment.