We present how we have developed a visualisation tool and text editor to display collocations for the purpose of close writing. Collocations are words that combine together in a natural way. Our design study approach brought together a collaboration of experts in lexicography, language learning, and visualisation, starting with low-fidelity prototypes before developing fuller functional systems. We studied the challenge of how to visualise collocations, such to help language learners write more effectively. We have co-created (i) an expert-curated dataset of over 30,000 collocations, (ii) developed a text-editor which performs word analysis, and recommends collocations, and (iii) created several in-situ visualisations linked to the editor, to help users visualise and lookup collocations, and view example sentences. Every stage of development has been evaluated with language learners and other potential users, which has positively improved its design and functionality.