Express Tools not available in AutoCAD Mechanical 2012
For installing the Express Tools in AutoCAD Mechanical 2012, you have to select to install them, checking the option in the Configure Installation page.
If you have already installed AutoCAD Mechanical 2012 without the Express Tools and you want to add them, from the Control Panel > Programs and Features > select AutoCAD Mechanical 2012 in the list, then Uninstall/Change.
When the installer pops up, click Add or Remove Features, check Express Tools and then Update.
By the way, after you have followed one of the procedures above, the Express Tools menu is not available in AutoCAD Mechanical.
In order to solve the problem, try this:
Launch AutoCAD Mechanical.
Write in the command line CUILOAD, then click Browse... and browse to/select this file:
C:\Users\<your username>\AppData\Roaming\Autodesk\AutoCAD Mechanical 2012\R18.2\enu\Support\acetmain.cuix
Load and Close and you should see Express Tools.
If, after that, clicking on some Express Tools commands you get the message: “unknown command”, do the following:
Write in the command line the command APPLOAD, in the following dialog load the files acettest.fas and acetutil.fas in the Express folder.