This fits on the PrintRbot with the Wade's extruder.
This is mounted on top of the laser module which is a snap on piece to the fan mount.
It needs simplification, and a one piece print.
I could see simplifying it by turning the mount around and combining it with the fan mount.
This design has 2 flat surfaces meeting and screw alignment.
There MUST be a laser / resister housing to attach the screws.
This mounts a $10 battery operated engraver from Amazon / Harbor Freight onto the bottom / front of a resister heat casing holding a laser.
The design traps the push button power switch in the 'on' state. The on/off depends on turning the battery compartment door at the end of the engraver.
3mm Filament holds the engraver solidly in place while the whole apparatus has some give because of how it is attached to the extruder head. It can swing about 10 mm off center in most directions, so there is a mild strain relief if it gets hung on something.
This doesn't cut deep, but it does take the top layer off of color laminated paper, or to cut through paper, and it can be used to sign prints.
The laser end cap doesn't fit the laser model, which is just as well, as its not necessary if the model is used instead of a resister housing.
You will want the Z end stop extender. http://www.thingiverse.com/thing:30590
It holds this http://www.thingiverse.com/thing:30260
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. http://www.thingiverse.com/thing:30590