General:
* Sculpter des citrouilles: This is the most literal translation and emphasizes the artistic aspect of carving.
* Découper des citrouilles: This is a more general term, meaning "to cut out" pumpkins.
* Creuser des citrouilles: This is a more specific term for hollowing out the pumpkins.
More specific:
* Graver des citrouilles: This means to "engrave" pumpkins, focusing on the detailed work of carving.
* Faire des citrouilles en forme de visage: This literally means "to make pumpkins in the shape of a face," and is specific to carving jack-o'-lanterns.
The best way to say "carve pumpkins" in French will depend on the specific situation. For example, if you are talking about carving jack-o'-lanterns for Halloween, you might use the phrase "faire des citrouilles en forme de visage."
However, if you are talking about carving pumpkins for a craft project, you might use the phrase "sculpter des citrouilles" or "graver des citrouilles."