Been using my little LASER for a while. I have a few more comments to share.
First, it works as advertised. Meaning there is nothing defective about the hardware or the software and how it was designed. That’s not saying it is the perfect small LASER engraver. It does the job.
It IS a low power (5.5 watt output) LASER so there are performance limitations that are not a fault of the equipment.
Some details need improvement. The wiring cables are necessary but create some problems in their routing. They need to be located outside the travel area of the moving parts. The stepper motors mount very low to the surface on which the engraver is placed. The legs on the frame need to be about 5mm taller. The wiring gets jammed under the steppers and the frame moves, spoiling the work in progress.
I built four 5mm high stands for the bottom of the legs using 3D printing. (See pictures.) The wiring will now not jam under the stepper as it travels. Taller stands would be useful if I ever need to engrave exceptionally high materials, such has the top or sides of a wood box.
The air assist is an absolutely necessary addition. Without the assist, the LASER lens opening gets filled with gooey black soot, blocking the beam. Gooey because the vaporization of volatiles in the material such as resins in wood make the smoke film sticker. The air assist quickly blasts this material away from the working burn spot, away from the lens. I see a lot of debris now collecting “downwind” from my engraver. (See 1st picture 2nd row.) It’s mostly condensed volatiles forming small granules.
The next comment is a biggie. I have said this before. The engraver really, really SHOULD be within a ventilated enclosure. Yeah, it doesn’t have to be and I can work with what I have. But the SMOKE is a really big problem. It must be managed. An enclosure with a vent pipe to the OUTSIDE is a very desirable feature.
The enclosure also manages the exposure to stray LASER light flash. The LASER is similar to the flash from electric arc welding. The UV exposure to the eye can be accumulative. The glasses provided with the engraver SEEM effective when worn, but I have no data how effective. It is an eye damage risk factor of unknown value. Another reason for enclosed operation.
Will I build an enclosure? Probably not for this machine. I can manage the risk. If I become more involved with LASER engraving, an enclosure will be the top of my list. I will also run a more power-full LASER, depending on intended use.
The 5 watt Diode LASER is an acceptable low cost entry into LASER engraving and limited cutting. In my opinion it is NOT a desirable production / commercial machine.
The recent and heavy “common home user” marketing of $2,000 – $10,000 LASER engraver/cutters on cable/TV is near criminal. They are presenting the “romance” of operating an expensive LASER in the home. The range of home products that “need” engraving will quickly fade.
I am a serious hobbyist and I have long had no idea how to justify the kind of LASER I would “like” to own and operate. I just don’t have a business plan to justify that kind of investment.
The same problem when I got into CNC routing machines. I am not a professional sign maker. A $10,000 overhead router is not justified. So I built a small router from basically scratch that does all that I need. It was also fun to design/build that router and its controls.
Bottom line. The new crop of low powered diode LASERs are fine for discovering what LASER operation is “all about” A great entry for the hobbyist but there are smoke control and LASER light exposure to consider.
With totally understanding of all the above, I enjoy my “playing” with LASER technology.
Cable will jam under stepper motor 
This is the standard leg height 
3D printed 5mm lift pad (under all four legs) 
Cable now clears under stepper. Note tiny black burn particles 
Height adjustment measuring cube. 
Good adjustment range remains