STL 3dit
An STL model viewer, editor, and creator for manipulating STL files.
...You can also insert 3D closed primitives.
The new STLX file format supports groups, materials, as wells as colors and generates much smaller files on average (compared to binary STL files).
NOTE: This latest build targets only 64-bit Windows Operating Systems due to the necessity of being able to manage (and navigate) very large 3D models.
Use the mouse and keyboard to move the camera around.