Click or drag to draw with symmetry Can remote or add clones of Pencil and attach MirrorX/MirrorY/MirrorXY/Swap blocks under their Transform custom block definition to alter their behaviour
There seems to be a bug in Scratch (11Aug2019) that forces me to add an extra (identical in logic) clone of Pencil at runtime, since the object named Pencil doesn't seem to always draw itself upon drag (its "symmetry" clones do draw fine)
