Model Builder Community

OK, so I have created a file with stone walls , with windows & doors but decided to change from stone to brick.

Is there an easy method without having to start afresh a new file?

No need to start a new file. Click to drop your new brick. Input the dimensions of your old stone in the material dimensions boxes top left corner of the design screen. Now right click the brick and select Order>Send to Back to put the new material behind all windows and doors. Delete the stone, move the brick into place. Hope this helps!
I can make a video tutorial on this at some point, it is a good topic!

Thanks, just tried that - now to work some more bits into the factory side.