Towards a Speculative Approach of Language Creation is a research-creation project involved in experimenting with practices of conlang as tool for speculating on how language can move differently. Looking at the field of constructed languages, its history and current practices, I establish how its alignment with the methods of scientific linguistics significantly limits the creative potential of sign-body encounters.  By going beyond the set of parameters framing what a natural language should be and what characterize a valid syntactic enunciation, I question the enforcement of rigorous method and reproducible patterns as premises for valuable practices. Building on this perspective shift in language’s founding principles, this encounter between conlang and philosophy is further extended into the field of art. A remodelling of the theoretical framework of the artistic is necessary to open conlanging activities to a plastic treatment of language. This reorganisation of what it means to create also demands an alteration of key notions such object, time and participation. True to an approach on research-creation inherited from process philosophy, I use this reconfiguration of the domains of language construction and art to launch a series of plastic experimentations. These investigations are presented in this thesis as an inventory of techniques, studying how language reverberates and is reinvented anew across a plurality of materialities.