What does a razor do

[The Compiler]

Hi volks,

I'm gonna put a psp-analogstick into my ds, and now I saw I need a razor. What exactly is that thingy, and what does it do? On  this pic I see four contacts. Couldn't I just wire up them to POn? What does the razor exactly do? A mate of mine etches boards by himselves, could he do me a razor (instead of paying 25$ plus shipping for one)?

Thanks in advance,

Florian