How to power 3 Laser array

I'm trying to build a set-up for my university.
It will have a red , green and blue laser, "stacked" on top of each other.

So the dots will form a vertical "line" of three dots, each dot spaced maybe a half inch apart.

These three beams will pass through a double slit, or any other sort of diffraction medium, and the results will be visible.

I want to run all of these ~5mW lasers with a single power supply, with the ability to turn any of the three on or off with a switch.

I don't really know what I'm doing at all, other than my design. I have moderate understanding of circuit analysis but i am unsure where to start with the electronics. I have no issue building the hardware bits.

any input is greatly appreciated!

thanks!

Here's a crude picture of the basic set up.

The lasers will be able to be aligned by hand.