Here are some ideas!
Using natural objects to create your own paintbrush. Explore what shapes and textures different things from the environment can make:
Use things you find in your garden or on your walk to print with:
Create a suncatcher by creating a frame and covering 1 side of it in sellotape, sticking pretty plants onto it and then sellotaping the other side.
Mix together some washing up liquid, water and a little paint or food colouring, blow into it with a straw to create bubbles and then place some paper on top:
Use wax crayons to make some bark and/ or leaf rubbings: