It fits the typical Greg's, not necessarily on a printRbot.

It quickly snaps onto and off of eddiema's printrbot fan mount.
It isn't a permanent attachment.

This is intended for what is usually a heat resister case with 2 screw mounts off the side of each end. I have a model in the list here. The laser model is slightly larger than the laser housing, 99% scale should make it the same.

The fan vibration shakes the focus lens to the point of falling out with this design. I made a snap on end cap to contain the lens. This model focuses about an inch and a half that way, which keeps the whole assembly out of the smoke and gives good clearance for the fan.

Using the fan, and its Gcode for power control through optocoupler and TTL to the laser controller, this can be used for photo sintering or signing plastic prints.

The engraver attachment is here thingiverse.com/thing:30520

You will want the Z end stop extender. thingiverse.com/thing:30590

I haven’t made the control interface yet, so all I have is on with power.

I'm working on it.
Its paused on the production end for a few weeks, as I design the printed circuit board for the TTL controller.

If you use 'lift' you can move the laser out of focus range and back in, I use 20CM. It gives the laser time to heat the next point enough to being sintering before the moveing begins. 1mmps at the fastest, 2 pass if possible.

The mark is .1 mm wide at 1 mm/ps on wood. 2 passes makes .2, and look better.

PrintRbot laser mount thingiverse.com/thing:30064

PrintRbot engraver mount thingiverse.com/thing:30520

PrintRbot marker mount thingiverse.com/thing:30999

PrintRbot Z end stop extender. thingiverse.com/thing:30590

My musings and tinkerings with this thing.
printrbottalk.com/forum/viewtopic.php?f=21&t=162