If you find your robot sliding around, adding a thin line of hot glue or other grippy substance to the toes of the front legs can help give it traction.
Googly eyes and other decorations are a fun way of personalizing your Stumble-bot.
You can use markers or crayons to add personal touches.
Some pipe cleaners can easily give your robot a more alien appearance!
If you enjoy CircuitPython and want to continue learning you can find lots more CircuitPython projects on the Adafruit Learn System.