This is a dual alignment laser for the Chinese laser cutters. This uses the really small (and cheap) 6mm laser pointer modules, which you can get for under $1 on ebay, DX, etc.

The laser cutter I purchased already had a laser pointer, but just a single one attached to the side of the head, which only points at the correct cutting spot at one point. Some people have made attachments that use two laser lines at 90 degree angles to each other, which always has the crosshair aligned with the cutter... but the biggest problem I had was making sure the object I was working with was at the correct height, so the cut/engraving was properly focused. So I decided to use two laser dot modules, which, when overlapped, will tell you that the object is at the optimal distance, and will point to the spot that the laser will cut (I don't really care where the laser is going to hit unless it's properly focused).

I designed the part in two pieces, which lets you individually slide the laser pointers around in all directions, so you can get the alignment set perfectly. The laser dot modules are slightly focusable, by turning the tip of the brass module... they usually have a small bit of glue that you need to break. I tried to adjust the focus to be nearly correct, though I also put just a small hole in the tip of the laser holder, which helps to cut down the size of the laser spot.

Attached are the STL files, as well as the Sketchup design files. You can see this mod, as well the rest of my CO2 laser cutter setup @ http://www.projectvb.com/laser_cutter/ .