A method of forming an imaging fibre apparatus comprises arranging rods to form a plurality of stacks each comprising a respective plurality of rods, wherein: for each stack, the respective plurality of rods comprises rods having different core sizes, the rods of different core sizes being arranged in a selected arrangement, and the rods of different core sizes being arranged such that each stack has a respective selected shape; wherein the selected shape or shapes are such that the stacks stack together in a desired arrangement; the method further comprising: drawing each of the plurality of stacks; stacking together the plurality of drawn stacks together in the desired arrangement to form a further stack; drawing the further stack; and using the drawn further stack to form an imaging fibre apparatus, wherein the selected arrangement of the rods in each stack and the selected shape or shapes of the stacks are such that the further stack comprises a repeating pattern of rods of different core sizes.