Sodastream makes home drink carbonators and they use metal takes for the CO2, which come with green plastic caps to protect the threads (which are mostly but not quite exactly standard CO2 fittings). The caps are easily lost or broken, and the are a generally awful green color (not unlike Thingiverse's STL renderer's default color).Print in your favorite color.SCAD file has several parameters which can be adjusted. Two STLs are provided - one mimics the default green caps, the other has two larger handles instead of ridges for grip.Can also be used to make other cylindrical caps. Specify the diameter of the interior of the cap, plus the wall thickness, and optional handles.