Wires! Did somebody say WIRES?
(wi 'r we here

)
SERIES connection: battery + --> switch one side --> switch other side--> laser1 + laser1- laser2 + laser2- laser3 + laser3- battery- --> battery -
Three 3v lasers will be OK, but if they are more than 3v, there may be a problem.
If they are indeed greater than 3v, connect in PARALLEL: all the - leads of the lasers are connected together and then connect to the - side of the battery.
All the + leads of the lasers connect together and then connect that bunch to one side of the switch.
The other side of the switch goes to the + side of the battery.
Using two AAA's in series (+ - + -) for the battery and connecting the lasers in PARALLEL configuration works also.
But getting a holder for two AAA's connected in series may be a pain....
hope this helps.
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Ei'luj