I posted this a long time ago, but I can't find it anymore.
For those who can solder or know someone who can solder, there is a pretty cheap alternative to a fairly accurate blinking sequence that can fit inside a hollow rangefinder. I've never touched a soldering iron before and I did this on my first attempt.
You can find a mini blinking LED kit here and I have found it at other electronic kit sites:
All you need to buy is the 9V battery holder and battery or 2AAA battery holder and batteries (longer wires) and you have nice blinky lights on your rangefinder. You can even add a mercury tilt switch from Fry's electronics and you're set .
Here is a picture of my old hollowed out rangefinder and you can see it fits very well in it. I'm sure it fits better in the other hollow rangefinders (Don't pay attention to the items I Xed out ).
The capacitor it comes with is 10uF which is shown in the first video sequence (Thanks to Brak's Buddy for the accurate sequences )
These are just slightly off, but who else but us would know .
The second video sequence is a green blinking LED (you should use a red blinking one ) about $1.39 at Radio Shack but you can get it cheaper on-line. I switched out the 10 uF capacitors and used 47uF ($1.19 each).
Depending on which sequence you decide, you can make this for under $15 (borrowing equipment if you don't have it of course )
Let me know if this helps anyone out.