That sounds like a fantastic idea for an eco-friendly art class! Making homemade milk glue and paint can be a fun and educational project for all ages. Plus, creating your own pigment powders adds an extra creative flair to the process. Here are some materials you can gather without breaking the bank or needing extensive preparation:

1. For Homemade Milk Glue:

   • Milk (preferably whole milk)
   • vinegar or lemon juice
   • Small saucepan
   • Strainer or cheesecloth
   • Small airtight containers for storing the glue2. For Homemade Pigment Powders: Various natural materials for creating pigments such as:
     • Dried flowers (es, marigolds, etc.)
     • Herbs (turmeric, paprika, etc.)
     • Soil or clay
     • Charcoal or ash
     • Berries (beets, blueberries etc.)
   • Mortar and pestle or small food processor
   • Small airtight for storing the pigment powders

2. For Milk Paint:

   • milk glue you prepared
   • Pigment powders ( the above step)
   • Small mixing bowls or jars
   • Brushes for painting
   • Surfaces to paint on (such as, cardboard, or wood)

By using these materials, you engage your class in a hands-on experience of creating their own glue, pigment powders, and paint from and easily accessible sources. This process not only teaches about art also about sustainability and the potential of everyday materials.

When choosing natural materials for pigment powders, ensure they are safe for handling and suitable for the age group you'll be working with. It's also good idea to have some reference materials or pictures of traditional pigment to spark ideas and inspiration.

Overall, this creative endeavor promises to be an enriching and eco-conscious venture for your class. If you need further details on the preparation or application of any of these materials, feel free to ask!