A powerful feature of decent CAD applications is a "block" library of symbols that can easily be inserted into a drawing. This allows you to reuse groups of objects without having to redraw them each time. If you are learning CAD, make it a priority to learn how to use the application block library. Being able to create and use your own blocks is one of the keys to being productive with CAD.
QCAD supports a block library and comes with some predefined blocks that you can start using right away. If the block library is not visible in QCAD, open it from the view menu (View -> Block Library)
QCAD Shortcut Command: GL (go library)
The problem with the QCAD default block library is the folder containing the blocks resides within the QCAD installation folders. If you add blocks to the existing default folders, there is a risk of losing them when you upgrade to a new version of QCAD.
A better practice is to create your own folders for blocks that do not reside within the QCAD installation. This also avoids the potential downside of losing blocks during an upgrade.
In this simple example, I created a new folder named /user/keith/opt/blocks.
To add the folder to QCAD, open the Application Preferences dialog from the menu (Edit -> Application Preferences).
QCAD Shortcut: Ctrl + .
Go to the Widgets | Library Browser section in the preferences and add your block file location. The new location will now show up in the block library tool.
QCAD is a 2D computer aided drafting application that works cross platform in Windows, Linux and MacOS.