Abstract: The container holding an artist's work can itself be just as expressive as the work it presents. We investigate self-curation as a creative practice, asking how artists explore and express their identity through the design of their own artwork presentations. Drawing on a study of artists' existing presentation practices, we developed Mylar, a malleable art presentation system that lets artists rapidly generate and compare provisional portfolios, seeing their work anew through different montages. We observed how 12 artists articulated, probed, negotiated, and foraged in Mylar, using rapidly generated portfolios as epistemic artifacts for reflection. We characterize self-curation as a reflexive and plural practice, in which artists use presentation design to shape the legibility of their self and their work and reflexively correspond with provisional presentations to reshape their curatorial intentions. We share design implications for expressivity in online art platforms and for malleable prototyping as a formative design method.