Looking for "Safe" (<=5mw) laser for astronomy instruction

[fogus]

I was out with my son (6) last night showing him some constellations. I used a tactical 5mw green laser to point out the big dipper, and it worked great. Brighter than was really necessary.

My main complaint would be that it was awkward to hold (due to the knobs). A comfortable laser would be really nice.

I saw custom-laser-pointers.com/btg-6-p-premium-green-laser-pointer but I couldn't tell if it was really worth $88.

I'd prefer 18650 power (and definitely a 100% duty cycle, but I don't think that's an issue with <=5mw).

 

[RA_pierce]

Z-bolt is a reliable company. I've bought several products from them myself over the past 10 years or so.
$88 is generally expensive for a 5 mW pointer. It looks like they're selling their "ruggedized" pointer for less. It runs on CR123As which are fine for a 5 mW pointer.
As far as I know, there aren't any truly 5 mW pointers available off the shelf that run on 18650s.
You're right that duty cycle won't be much of an issue for a low power pointer.

For around $80 I could put something together for you that runs on 18650 in a spare flashlight host I have lying around. It's not the best looking host, but it'll get the job done. I can set the power to 5 mW (I have a power meter to verify).
I have diodes in 520 nm and 505 nm on hand. 505 is a "bluer" green and is closer to the human scotopic (dark-adjusted) vision peak sensitivity. Aside from enhanced sensitivity, the short wavelength is scattered more by the atmosphere, so the beam comes out a little clearer which gives you the most visibility at a safe power level. Another advantage over the Z-bolt pointer is that it's a direct diode pointer so it's much less sensitive to temperature variation. In my opinion, 505 nm is the best wavelength for an astronomy pointer.
Send me a message if you're interested.