What piezoelectric materials can be made at home?
The top of my list for exhibiting piezo activity and can be easily purchased and is also transparent..

Quartz

That's about it. It's used everywhere - as an oscillator for quartz crystal watches, quartz crystal microbalances, etc.

Most of the other piezoelectric options:


Lead Zirconium Titanate (PZT)
Barium Titanate ($\ce{BaTiO3}$)
Zinc Oxide ($\ce{ZnO}$)


Aren't transparent. They're white ceramics. You can easily purchase them online from most scientific supply companies, but they don't meet your transparency criteria.

Polyvinylidene difluoride (PVDF) is claimed to be transparent (e.g., here) but you would need to apply a high electric field to pole it, and if the formulation isn't crystalline enough, you may not get a high piezo response.

My group is designing some materials that would be good, but they're still in the research stage. Stay tuned.