A single structure usable as a backup shoe or element retainer in a packer assembly for sealing a wellbore can be fabricated using an additive manufacturing process. The single structure can have a high-density region and a low-density region having a density that is lower than the high-density region. The low-density region can be deformable to retain a position of another component downhole in a wellbore, such as an elastomeric element useable to expand to create the packer seal within the annulus of the wellbore. The high-density region can include a ribbed-structure to reduce circumferential force applied to the single structure.