how should i attach door caps?

i was wondering how i should attach my door caps? i looked around and cant find any tips. should i bolt them on from the inside, or should i fiberglass them on somehow? and the same goes with my sideskirts. if anyone has done it themselves or has any input it would sure help.

the door caps attach with douvle sided tape, well at least mine do. What kind of car do you have, usally bumbers, fenders, skirts are mounted in the factory bolt locations.

if the door caps are attached with tape couldnt someone just come pull on em and theyd come off? i would think that tape would wear out after a certian amount of time like after bieng washed or in the rain normal stuff like that.thanks for the idea though. and i found instructions for the sideskirts just had to keep looking a while