You should avoid laser cutting ABS. Apparently it releases highly toxic gases / 'cyanide gas'. Ref: http://atxhackerspace.org/wiki/Laser_Cutter_Materials
ALL plastics release highly toxic gases when laser cut. Laser cutting is extremely nasty! The machine exhaust must really work, and then you have the wait times before opening the lid. With acrylic, I wait at least 5 mins and with ABS, 15 mins. You also need to consider what happens to the exhaust. We had a problem with cutting acrylic at the former location of the hacklab because it was in a residential area. For that reason, we built activated carbon filtration system; in the end, it did work fairly well.
Go google it, it's kinda difficult to find proper data or reliable sources on ABS laser cutting, only forum discussions by total amateurs (like me, to be fair!), and random hacklab rules referring to nothing, or at best, to those amateur comments. The fact that they just list all possible dangerous-sounding byproducts for ABS, but totally ignore the similar list for PMMA which they want to cut, shows that they have no freaking clue what they are talking about, and just want to prove their bias using difficult chemistry words they can copy-paste.
I quote a good comment regarding forum fearmongering:
"There is virtually nothing that you can laser cut that generates fumes that are safe to breathe. That includes materials like paper and wood. The problem with using the MSDS as a criteria is that there is no way that the average person who does not a degree in chemistry, biology, and medicine (maybe even another degree or two) can really make an assessment of the true risk. It always pays to be cautious, but I have looked at plenty of MSDSs and it is pretty difficult to make a judgment as to the safety of laser cutting" (source:
http://www.sawmillcreek.org/showthread.php?144771-ABS-laser-safe&s=67e340c9c51708a3e4efbc85dadf940e )
If ABS produced such freaking amounts of HCN and other gases that kill you, we would have problems with accidental ABS fires; it happens all the time.
I don't have proper data, but it's a ridiculous assumption that the gases from PMMA are just fine and dandy and ABS instantly kills you. AFAIK, they are maybe one order of magnitude apart, at most. Hence, the recommendation to only cut small amounts of ABS, respect the ventilation times before opening the machine, and so on. General extra carefulness, limiting the exposure to the minimum possible.
But demonizing ABS and going on with your life laser cutting other materials sounds like a textbook example of the False Sense of Security.
I repeat, laser cutting is nasty! You do careful tests and you need to know what you are doing.
From the link you posted, I quote: "ABS does not cut well in a laser cutter. It tends to melt rather than vaporize, and has a higher chance of catching on fire and leaving behind melted gooey deposits on the vector cutting grid. It also does not engrave well (again, tends to melt). " In my
real tests, ABS seems to cut just fine, without "melting" too much, without any slightest trace of any goo going anywhere, and the engraving looks OK too. It's not perfect like PMMA. Maybe they are discussing thick sheets of over 2mm or something, but they don't give any sources nor data, just authoritative order, which, of course, is just fine, you go by their rules when you are over there, but it doesn't help when discussing the matter outside their club.
For the OP, I'd recommend CNC milling, too, but just giving my $0.02 regarding my very successful prototyping using laser cutting on these same Hammond ABS plastic ends, with absolutely no problems whatsoever, but OTOH, I'm only doing a few of these boxes. Each box has 25 connector holes, 4 LED holes, 28 ventilation slots, and two fans with large cutouts + screw holes, and a lot of text as marking, so they are not that small. If OP has something smaller, the gas problem will be easier on them.