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Hi HAELEY,

It is not possible in AutoCAD for Mac, there is no such Express Tools command.
If you need to convert small portion of text, you can also look at this thread:

https://forums.autodesk.com/t5/autocad-for-mac-forum/3d-text-in-2013-for-mac/m-p/3712240#M5453

Or ask some AutoCAD for Windows users to convert text for you.

Plus, BricsCAD fro Mac can do such task.

Maxim