How to convert a model from "LEGO Digital Designer" Extended into non-Extended? I'm using LEGO Digital Designer. My LEGO model I've designed uses parts that don't exist. This is a bummer because I am trying to buy the parts to realize my design in actual, physical LEGO bricks!

I hypothesize I created this file not noticing which mode it was in. My only recourse now is to somehow "scrub" the design of these invalid parts.

I'm using LEGO Digital Designer 4.3. When it starts up, it shows 3 tabs:


LEGO Digital Designer
LEGO Mindstorms
LEGO Digital Designer Extended


As I understand it, LEGO Digital Designer Extended is a distinct mode from LEGO Digital Designer. The distinction is, Extended lets you use pieces that aren't in production. For example, you could pick a shape and color combination that have never been manufactured by LEGO.

How do I convert it to non-Extended mode? Alternatively, how do I figure out which pieces in my model are "illegal?"

One solution I've been experimenting with:


Export a .ldr file
Importing the .ldr export file into another program
The invalid bricks will be dropped, and from there they can be replaced


I'm on OSX so the ones I've successfully tried are:


LeoCAD
Bricksmith
Copy and paste works:


Open the model in Extended mode
Copy the design
Close the model
Open a new, empty document in "Standard" (non-Extended) mode
Paste the content


The bricks that does not exist in Standard mode will not be shown, leaving gaps in the model.