Tissue thickness compensators for use with surgical staplers that are configured to form staples having different formed heights. Various tissue thickness compensators are disclosed that have non-uniform cross-sectional thicknesses or profiles. The tissue thickness compensators may be formed with a surface that matches a non-planar surface of the anvil or the staple cartridge deck. Methods of forming tissue thickness compensators with non-uniform cross-sectional thicknesses or profiles are also disclosed.