An exceedingly simple yet aesthetically pleasing pen program. Press space to switch background color, although I would personally recommend black. Please look at my pen projects studio here: https://scratch.mit.edu/studios/28267968/
pen #4: https://scratch.mit.edu/projects/460995824 pen #3: https://scratch.mit.edu/projects/459807691 pen #2: https://scratch.mit.edu/projects/459804034
