Many manufacturers in different industries provide libraries of blocks for their products for use with AutoCAD and AutoCAD LT. Some are free while some may have a fee associated. AutoCAD versions up through 2018 include the SEEK command, which will launch a web browser to BIMobject, from which free downloadable symbols were available. CAD blocks are named groups of objects that act as a single 2D or 3D object. They’re used to create repeated content, such as drawing symbols or standard components. With AutoCAD and AutoCAD LT software, you can create your own CAD blocks or choose from a large library of pre-made blocks, including. Free products are subject to the.

Solution:

Autodesk Free Blocks

AutoCAD and AutoCAD LT have a limited set of symbols which are available on the sample tool palettes. One can find an icon on the Ribbon panel -> View tab -> Palettes panel, to launch the palettes. Alternatively, one can use the keyboard combination CTRL+3 to access the same palettes. That said, that is the sum of the symbology available within the application.

Some symbols can be found in the sample files that come with AutoCAD. These are located:
C:Program FilesAutodeskAutoCAD 20xxSampleen-us
There are however other resources available for block libraries, the following are just a handful found using a Google search:

2d Cad Files Free Download