This thing is a mount for a laser cutter on an Ultimaker 2 3D Printer. It was specifically designed for the JTechPhotonics laser but may work for others of the same form factor. There are also a number of other sub-things in the two zip files that I used to mod my printer to be a cutter.
My goal with this design was to have the laser be easily attached and detached from the printer, while being secure and stable, and allowing for a maximum of the build platform to be available. The mount slides under three of the four screws on the top of the extruder assembly for ease of attaching and detaching. I added connectors a foot or so above the mount so that the main part of the cabling for the laser and fan can stay attached to the printer between uses. I can change between printer and laser cutter in about a minute.
More on my blog: http://raspberrypirobot.blogspot.co.uk/2016/11/final-configuration-for-um2-laser_21.html
Custom supports are recommended for both parts. The part that is shown in the picture was printed in PLA but I suspect that a higher temperature plastic might be a good idea. I have another copy printed in Colorfabb NGEN waiting to go on if the PLA warps.
Makes sure to clean the support from where the mount and the fan cowling mate so that you have a good join (unlike the one in my picture). You may find that you need to warp the mount and cowling into place a little if you do not. Raising the temperature of the plastic a bit and holding it in place will work but care is needed :-o