A thermoformed product formed during a thermoforming process includes a thermoformed sheet of polymeric material having front and rear surfaces defining a thickness, and having a first section thermoformed to include a non-planar three-dimensional useful structure and at least one second section. Each of the at least one second sections have a first area of reduced thickness and have a second area including attachment structure, with the attachment structure being formed in part by material extruded from the first area into the attachment structure while the polymeric material of the sheet is hot during the thermoforming process.