This design is a printed protection for the laser modules used in laser cutting/engraving. It also works as an air assist head.
I designed it for laser modules with a variable focus lens. The top part of the protection is clamped on the focus lens ring by two M3 screws. The focus ring should be 21+-2mm for this design to work.
You can find different versions of the design depending on your needs. In the files names the first number correspond to the parts height. You should choose it to be slightly smaller than your focus distance measured from the bottom of the focus ring. "Single layer" designs only have the air assist function while "double layer" designs have a second layer designed to shield you from the laser's reflected light.
The air intake is designed to accommodate a 6mm flexible tube connected to pressurized air.
I print it upside down to minimize the need for support, but supports are still necessary for the print to go well. On this subject you may refer to the images of the slicer i added.