I’m looking for a <5mw laser powered by the 18650 battery. Why?
I want a very long life cat toy or something for the office that never needs batteries. Most lasers tend to drain batteries quickly, so I want a lower powered, high capacity setup.
Anything out there like that?
Although I think this is still too powerful to be a toy. I’m not sure how the MW scale works but check this place out anyway. They have a bunch of lasers that take lion batteries. They are a good company with half way decent shipping times.
This is how I would do it
Go to scifilasers they have a p60 dropin heatsink”$6.50 dropin heat sink”
http://www.sflasers.us/501B_Heatsink/p2035127_10207418.aspx
Then buy the cheapest dropin laser module you can get on eBay $2-3
“If you have a cheap pen type just Harvest the module from it and tape the switch down” The host is cheap if you don’t have one
Total spent $10-15 including host
And the best part you can get US sourced parts and have it done within a week instead of waiting a month to get something from china
Survival laser has something similar but it’s a nicer c6 host so it will cost a few more dollars ” C6 host “:http://www.survivallaser.com/DIY_C6_Host_Assembly/p556088_5715278.aspx
Host costs $10 heat sink $7 then cut up a cheapo laser pointer and install
Still less than $20
Hope this helps
there is a good chance that and similar lasers will be 100~200mW, or at least far greater than the common <5mW rating or whatever. you can’t trust ebay and many seller ratings since they know labeling anything higher will result in it being removed due to many government import regulations.
Unfortunately it's not always that easy to find a lower power green laser.
I would highly advise against either of the two above options, if you plan to use the laser with with a cat or a dog. My own experience with testing ~30 cheap, so called 5mW lasers, is that they almost invariably end up being overspec. Typically in the 20-40mW, range, but sometimes higher.
Unless you're planning to leave the laser on for extended periods of time, a 5mW good laser pointer running off two eneloops will last a long time.
I suggest either of the following companies, as they will give you a quality laser guaranteed to be under 5mW;
Very good point
And I would stay away from green laser due to the IR pulsed from them
infiitus would be the expert 
also, i hear that there is often a pot on the drivers which should allow you to tune the power yourself to some degree?
The green lasers from laserglow, or optotronics have IR filters in them.
As an alternative, there are a ton of red laser pointers out there, and those tend to be 5mW or lower.
I use a 20 dollar Rosewill infrared thermometer with a built in red laser. It takes two common AAA batteries which last forever. I’ve had it probably 3 years on the same set of batteries and I use it to play with the Chihuahuas almost every day. Plus, I get a readout of their current temperature and it’s great for heating the pan for grilled cheese sandwiches haha. In fact, one of my Chihuahuas, Zoey, looks for the red dot if she sees me taking out the ingredients for a grilled cheese. She’s pretty sure that whatever that red dot is, it’s out to steal our food.
Something like this
Laser Doggles! 
Omg! We will be the coolest ones at the next laser meet!
Infinitus, you don’t think there any low powered options using a 18650?
Not really not. There is just no point in driving a 5mW laser with a 18650 battery... it's like strapping a fuel truck onto a prius.
You can try contacting http://jetlasers.org/content/5-contact-us though. They can probably make a laser like that easily.
