This was the original outlook of the Apple adapter.
After we modified it and polished it, it becomes:
(Actually no change in outlook, but has a change in output voltage from 24V to 14V ^^)
The below photo is showing the original outbook of the bottom of the adapter:
After modification, it becomes:
(Also no change in outlook :-D)
However it seems unavoidable to have cracks on the shell of the adapter, like the pic below ... as it was crack-opened by us previously. So if anyone of you knows the way to open the Yo-Yo adapter beautifully, please tell us by mail.