I have had a few ideas for this, so hear me out:
Ingesting dust directly: When Hazel stabs crystals into his arms, the effects of the dust were transfered to him, so what if someone were to eat dust? In that event, would this grant a short term boost to the body, do nothing, or permanently change the body?
Mixing dust powder: Definately dangerous, but what would their effects be? Could this give rise to man-made dust types? Would the different dust types work seperaterately, and thus the same as just using two types of dust? Or would it cancel itself out, and not work at all? And if it does combine to make new dust types, what could they be? Fire & Water. Lightning & Gravity. Wind & Ice. What would they do?
This ones a question: If hazel were to stab gravity dust into his arms, would he float, or would he gain control over gravity? If the later of the two, how much control?