In some examples, acoustic panels (such as for gas turbine engines) and techniques for forming acoustic panels. In some examples, the acoustic panel including a coversheet including an outer face, an inner face, and a plurality of apertures extend from the outer face to the inner face. The acoustic panel also includes a 3D-printed support layer including a lattice structure formed at least partially of a polymer, the lattice structure defining a plurality of cells of the support layer, wherein a first side of the support layer is coincident with the inner face of the coversheet.