With the RSJ frames made in video "010 DA3D Creating the Barns RSJ Frame", this video continues the project by adding the purlins and curved corrugated roof.
If there is anything in these videos you haven't understood, please check the Getting Started videos, 001 to 008 which will probably help with your understanding. If you are still struggling, either leave a comment below and I will try to get back to you when I can. Otherwise you could ask a question on the DA3D post in the Tutorial , Tips and Tricks section of the Blenderartist forum at: https://blenderartists.org/t/free-det...
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Check out more about learning Blender on my websites:
http://www.robertburkeillustration.co.uk
http://www.rab3d.com/index.php