Disk test structures are useful for testing physical properties and painting/finishing techniques for various materials. Nine disks are sprued together and may be separated with a small cutting or snipping tool. Each disk is one inch (2.54 cm) in diameter with 40 mil (1 mm) wall thicknesses. Note that one side of each disk is flat and the other side is cupped. The cupped side allows you to test materials for porosity with various paints or finishing solutions.
The oval shaped geometry is included on the sprue section to identify that the test structure has minimum geometries of 40 mils. This helps to limit confusion between test structures which appear similar but have different minimum geometries.