This bracket snaps over the mounting magnets on the 0.5W 405nm engraving laser from banggood. It uses the side of the extruder fan house to provide a repeatable mounting position for the laser module.
It helps to loosen the screws holding the magnets before trying to snap the bracket onto the laser module. Once the 4 magnets are in the bracket, tighten the magnet mounting screws.
Openscad source is included if you need to tweak hole sizes or positions. This design could be reconfigured for other size housings.