By using this design (complete with magnetic timing control) and an intuitive xor gate, we can adapt the model of the one-bit full-adder proposed originally for Belousov-Zhabotinsky medium . The xor gate can be replaced with an or gate without loss of logic, as there is no situation where two LMs will arrive simultaneously. The design schematic can be seen in figure . There are two sets of electromagnets, which cycle on-off in pairs; first EM1 releases, then shortly after EM2 releases. This maintains synchronisation between LMs across the two collision gates. For this design iteration, we have used channels for the passage of LMs. This is a deviation from pure collisionbased computing, where free-space is used as momentary 'wires' on an ad hoc basis. However, in this case, we believe the use of channels to be an important intermediate step towards this goal. Based on the observations of our collision gate, we note that such a full-adder could be implemented with dimensions of approximately 15 cm × 15 cm, using LMs with a volume of approximately 10 µl, and a LM precollision run length of 2 cm. This gate could then be cascaded as required to produce an n-bit full-adder. Empirical testing has shown that reliable and manipulable LMs can be formed down to 1.0 µl, meaning that the device could then be scaled down appropriately. Using a single set of syringes, the automatic marble maker can up to eight LMs per needle per second. At this speed, synchronisation of the electromagnets becomes both more crucial and more tricky -potentially requiring computer control. Initial investigations into the collision lifetime of the LM are promising, with six 3 mm LMs confined to a 2.5 cm × 2.5 cm space on an orbital shaker at 100 rpm, showing no signs of wear after three hours.