Four watertight (solid) Utah Teapot Models converted from obj format.
When all color values are the same, simplify conversion to Material or single-color ColorRGBA/Color node in X3D-Edit and X3dTidy
When alpha is always 1, enable conversion from ColorRGBA to Color node in X3D-Edit and X3dTidy
Meshlab X3D Exported, http://meshlab.sourceforge.net
X3D-Edit 3.3, https://www.web3d.org/x3d/tools/X3D-Edit