The level of skill this takes is literally insane...I think this guy is a master craftsman. Not saying it can't be done, but its probably not as simple as you think. I once made a Raspberry Pi fake iMac G3. Empty iMac case, 5 dollar monitor from Goodwill, ta da, done. I modded Ubuntu Mate to look somewhat like the Mac OS and then I gave it away, which I now regret.
I search on youtube for stuff like this, searches like: PowerPC, PowerPC Linux, Powerbook G3/G4, ibook G3. Filter search for this year to avoid all the ten year old looks like they were shot with a potato videos that inevitably crop up. Demonic Sweaters is a cool NYC mac/linux guy, he put a Raspberry Pi into a Mac SE/30.