I'm a big fan of Reeves' book, the Complete Tutankhamun, in which he first talks about the composition of the funerary masks and speculates that one was originally made for Smenkhare. As a starting point, I suggest reading his 1997 article The Tombs of Tutankhamun and his Predecessor based on a lecture delivered at the Bloomsbury Summer School, The Valley of the Kings Revisited, University College London, 17 May 1997. He says:
"A second and more sobering implication of my hypothesis is that a second Amarna cache, containing the weeded burials of Kiya, Meketaten and Nefertiti-Smenkhkare - the remaining, unaccounted for occupants of the Amarna royal tomb - still lies undiscovered in the Valley of the Kings. For, as with the principal occupant of the Tomb 55 cache, the burials of at least one, and perhaps two, of these individuals seem to have provided a range of materials for Tutankhamun’s reuse and must, themselves, have been subsequently re-interred somewhere."
He has now updated that theory and the evidence is very convincing that parts of Tutankhamun's golden mask was made for a female Pharaoh by the name of Ankhkheprure Nefernefruaten whom he equates to Nefertiti. I'm not convinced that equation should be made. Names were in short supply within the Amarna royal household, which is why we have Neferneferuaten-Tasherit and Ankhesenpaaten Tasherit. The history of the period between Akhenaten's death and start of Tutankhamun's reign is ... well, decidedly uncertain. At least one and probably two pharaohs occupied the throne during that time - possibly as co-regents. (I've never understood why there is no suggestion for a co-regent for the start of Tutankhamun's reign.) If the KV55 mummy is Akhenaten then the tombs of these pharaoh(s) and of Nefertiti are unknown. Reeves also suggests that the mummy of Meketaten should form part of the group transferred from Amarna and I remain of the view that the KV55 mummy is actually Smenkhare. Anyway - read his articles. It is well worth it.
(PS if you like food, then Sherry's main web site is Jefferson's Table. Her latest recipe is Mr. Jefferson's Ice Cream Sundae with Brandied Peaches and Praline Crumbles.)
(Image from Wikimedia Commons)