To date, slicing algorithms for additive manufacturing are most effective for favourable triangular mesh topologies; worst case models, where a large percentage of triangles intersect each slice-plane, take significantly longer to slice than a like-for-like file. In larger files, this results in a significant slicing duration, when models are both worst case and contain more than 100,000 triangles. The research presented here introduces a slicing algorithm which can slice worst case large models effectively. A new algorithm is implemented utilising an efficient contour construction method, with further adaptations, which make the algorithm suitable for all model topologies. Edge matching, which is an advanced sorting method, decreases the number of sorts per edge from n total number of intersections to two, alongside additional micro-optimisations that deliver the enhanced efficient contour construction algorithm. The algorithm was able to slice a worst-case model of 2.5 million triangles in 1025s. Maximum improvement was measured as 9,400% over the standard efficient contour construction method. Improvements were also observed in all parts in excess of 1000 triangles. The slicing algorithm presented offers novel methods that address the failings of other algorithms described in literature to slice worst case models effectively.