By positioning an electromagnet (100 N, 12.0 V DC, 29 mm × 22 mm) behind the acrylic slope, the rolling LM can be captured and released at will, by the switching on and off of said electromagnet. By controlling multiple, spatially-isolated electromagnets in series, non-concurrent LMs can be easily synchronised. To our knowledge, this is the first time electromagnets have been used to provide timing control with liquid marbles.