You can save your custom tools so you can reuse them in other GeoGebra constructions. In the Tools menu, select ‘Manage Tools’. Then, select the custom tool you want to save from the appearing list. Click on button ‘Save As…’ in order to save your custom tool on your computer.
Note: User defined tools are saved as files with the file name extension ‘.ggt’ so you can distinguish custom tool files from usual GeoGebra files (‘.ggb’).