Finger paint blackberries and add vines for them to hang from using pencils and crayons.
Take impressions from blackberry leaves by painting both sides and placing them on one side of a folded piece of paper, when ready fold the paper in half and gently press together. Open out and reveal the imprints.
Small acrylic paint brushes for leaves - acrylic or plastic to avoid animal by-products
paint dabbers or
daubers as an alternative to fingertips
blackberry vine line drawn picture
The use of bramble leaves will come at risk. Check each thoroughly to break down as many soft thorns as possible ask, or ask to see if anyone has a
thornless plant they'd share some leave from.