When you export a custom transformer, it is saved to a separate .fmx file. This means that you can open and edit it just like a regular workspace, and you can share it with other users. Custom transformers can be:
edited independently of any workspace
shared with other users (via e-mail or shared directories)
embedded or linked in any number of workspaces
How to export a custom transformer:
Open or create a custom transformer.
From the File menu, choose Export Transformer. Another instance of FME Workbench will start, and the transformer will appear on the new canvas. The title bar will display the transformer name (an .fmx file) and the following default location:
C:\Documents and Settings\<user>\My Documents\FME\Transformers
Exit Workbench.
Go to your FME\Transformers folder to see the new transformer:
See Sharing Custom Transformers and Installing a Custom Transformer.