How do keyblades work when they put a new key chain on does it just transform or does it have to be a special key chain

For what ever reason they never got much into the mechanics of Keychains but generally they seem to be made out of memories (?) and transform the Keyblade when attached. I presume the Keychains have to be spacial but it'd be great if Sora could walk into any store and buy a regular 'ol Keychain. Like...

 

*insert something humorous here* 

I dunno, I think that they transform the keyblade based on what the keychain means to the weilder. Ex- When sora put Kairi's good luck charm on the keyblade to create Oathkeeper.

I dunno, I think the only time we actually saw a canon transformation was when Roxas lifted the Kingdom keys up at the end of Days.

The mechanics of a keyblade are given just a little more than zilch explanation.  There's nothing in the games that explains it and I don't know if it's ever explained in outside sources.  The keychains seem to transform keyblades into reflections of the worlds/people they came from, and given the tangible effect memory can have in the KH universe, something like that is probably the only explanation for it.

I always thought you just put the keychain on and BOOOM~

I always thought you just put the keychain on and BOOOM~

i had a similar thought,only i had it changed that the keyblade would dissapear for a second(like being desummoned) and then get resummoned as the new key.

though seeing how Roxas changed his dual keyblades,your explanation is more plausible i guess.