[quote=@tobiax]
Other than the fact that powerless masks can sometimes/typically do have different shapes than their Great forms, and the aforementioned issues (unless her mask will transform when she does, as will those on my Toa, to a Kanohi Huna for Vhis, and a Kanohi Rahkuta[Mask of Rahi Control] for Hura.)
[/quote]

Fact checker on this bit:

Kanohi masks are made from kanoka disks, and the type of mask depends on the blend of disk types used. The power level depends on the power levels of the disks. It is then forged into a shape corresponding to the mask's disk combo to mark it as that type. The great and noble masks of each type have different shapes, but there is no designated shape for a powerless kanohi, so these masks are forged in either the great or noble shape, eve though the have no power (think of Hahli's kaukau and Macku's huna - both powerless masks, but one in the great shape, one in the noble).

This means that, when a matoran becomes a toa or a toa becomes a turaga:
The mask changes power level, which changes the shape.
The mask's power cannot change. It is still made from the same base kanoka, but has now moved to a different power level.

As a side note, it is possible but unusual to forge one mask in the shape of another. For example, if a mask were made from level 7 enlarge and regeneration kanoka, it would have the properties of a noble hau. The mask maker could then pour the molten mix in a great ruru-shaped mold, making that the shape of the final mask.

This isn't often done, as the point of standard shapes is that you can know what a powerless mask was made from just by looking at it. That isn't to say it never happens though. Vhis's mask may have been made from a blend of enlarge, shrink and freeze disks and then forged into the shape of a great volitak by mistake. This would explain how she thinks she's been wearing a volitak her whole life, but on becoming a toa, discovers that she wears a huna.