An airtight container can be as easy as a CLEAN 4 gallon ice cream plastic tub! Use some dish soap and bleach, RINSE REALLY WELL, and make sure it is perfectly dry before using!

Also - those large plastic containers that restaurants use for their supply of pickes, etc - they are great for storing larger amounts.

The cats' food bowls are glass, and the water dish stainless steel. These others are for storage only.

Good luck with Mr. Picky!