door speakers, crossover for tweeter in the door?

is the crossover for the door tweeters in the door?

is it wire from stereo (or amp) running out to doors and crossover is in door somewhere or on the midrange speaker and then wire out to tweeter?

I have some sets of speakers with configurable crossover for the seperate tweeter...

anyone find tweeters that fit in the door or do you make your own grill/housing for tweeters?

thanks!