Making a ROM isn't that easy, I think... You have to set up a build environment, pick the function related codes from CM's source, sync AOSP's source and see if they compile nicely together. Not as simple as replacing files. Plus, usually we don't call it a new ROM if it's just replacing apps, ringtones and all that.
Sent from Samsung Captivate Glide @ CM10.1.2
Google Nexus 4 (CM11 Nightly)
Samsung Galaxy S Relay 4G (CM11 Nightly)
Samsung Galaxy Nexus (CM11 Nightly)
HTC Incredible S (CM11 Unofficial
Samsung Epic 4G (CM11 Unofficial