i would like the build fighters stuff more if the actual kit translated into being able to do that.
as it is, unless you fabricate adapters and pieces, you likely aren't going to be able to mix and match different kits together unless they're in the same series.
like seed stuff isn't going to be able to have any 00 stuff on it, for example, because of fundamental differences in how the pieces (arms, legs, backpacks, chests) connect. heads you could probably do, they're usually just a ball joint socket
see my gundams here
https://imgur.com/a/F7xKM5r
updated 04/09/25; hg black knight squad cal -re. a