The slots could be laser cut (after the installation of an industrial extractor). Any other ideas??
Good to have met you on Friday - I’m the guy you were chatting to most of the time. 
In terms of what we have, I think the simple way to approach this is what i mentioned - that we mount the Tolapoint into a machine vice, and use a guide to feed it into a Dremel style slit tool.
I have some Dremel accessories on the way for the space, as we’ve certainly needed some for a while. As such we might be able to try out the slot cutting tomorrow evening!
The problem with ABS is not toxic byproducts, but that it really doesn’t laser very well. It tends to melt rather than vaporise, which creates a fairly messy edge and also has an increased chance of catching fire. Much as I love the laser, it’s not the ideal tool for every job