Many of the laser pointers you can buy from amazon from china are going to contain an internal barrel shaped laser diode and small circuit board... like this one:
Once you liberate the internal electronics from the battery connecting tube, you may want a way to mount it to another substrate. This thing can help. I had already begun to build a laser kaleidoscope with several DC motor mounts, so it seemed like a good idea to reuse the design file from that and resize the cavity to 13mm to accomodate the laser. It worked great! I have included a slot at the top for a zip tie to cinch the two parts closer for a friction fit, but in reality the size was close enough to the diode that I was able to pry the two halves apart slightly, insert the diode, and it was clamped tightly automatically.
update: I've since encountered alternative laser diodes with slightly larger diameters, so I'm including them here in case that's easier for you than to resize the file yourself.
update 2: Cute overload!! I received a couple of laser diodes in the mail and they're only 6mm in diameter!!
Autodesk inventor fusion file included. Have you tried inventor fusion? It's pretty nice and it's free!