Re: Advice please?
What do you mean by, "metal thing"? Do you mean the host?
The two input leads to the driver need to be connected to either end of your power source, in this case your batteries. A switch in series with the batteries will obviously allow you to turn the laser on or off, whether you choose a momentary or clicky type switch.
If you use the host as the positive power rail, you are using the spring in the end cap to complete the electrical circuit rather than having to run a wire past the batteries to connect. With Bluray diodes, the case pin, (electrically connected to the outside casing of the diode), is floating, in other words it is not connected to any part of the diode chip. This means that you can choose either the +ve or -ve to run through the host. This is what determines which way round your batteries will go in. This is only the case with BR diodes so beware!
If you come to build a red laser, the case pin is internally connected to the negative pin of the diode which means you are bound to using the host as a negative conductor, (if you choose to use the host as a conductor that is).
I hope that's what you need.
M
