You can buy a space case(I think it's the space case, something like that anyways) which passively collects the keef through a screen. You have to shake it for maybe a good ten minutes, but you can get a nice little brick of hash if you have a press. Or a whole bunch of keef. I'd take the keef, personally.

Oh, and the crystals are the trichomes, which contain the highest concentration of THC. If that was the last guy's question.