Where was Grond made? Barad-dûr? Orodruin?

Question

@Jimmy Shelter's answer stated (regarding Orodruin, post-One-Ring-making):

Potential evidence of a future use of it was for making the battering ram Grond in the War of the Ring.

LOTR Wikia contains uncited statement, instead pointing to Barad-dûr:

Grond was forged in Mordor by Smithies of Barad-dûr during the final years of the Third Age, specifically for use by the army besieging the city of Minas Tirith in Gondor. It shared its name, in homage, with the "Hammer of the Underworld," a great mace wielded by Morgoth, Sauron's former master.

Is there canon support for either of those theories, especially Orodruin one?

In LOTR itself, I found no mention of location beyond "the dark smithies of Mordor":

Great engines crawled across the field; and in the midst was a huge ram, great as a forest-tree a hundred feet in length, swinging on mighty chains. Long had it been forging in the dark smithies of Mordor, and its hideous head, founded of black steel, was shaped in the likeness of a ravening wolf; on it spells of ruin lay. Grond they named it, in memory of the Hammer of the Underworld of old. Great beasts drew it, Orcs surrounded it, and behind walked mountain-trolls to wield it. (The Return of the King)

Answer 1

For clarification, a little explanation is in order. A 'smithy' is a forge; a blacksmith's workshop and Sauron trained as a blacksmith under Aulë.

Sauron learned metal working from Aulë, his first "mentor". He later 'turned to the dark side' and became the top student/Lieutenant of Melkor/Morgoth. He even taught the great Elf craftsman Celebrimbor the fine art of metalworking (and ring making).

Sauron was already set up with his own smithy to forge whatever he wanted so it makes perfect sense that he would make Grond in his already established facilities.

When Sauron chose the land of Mordor as his dwelling-place in the Second Age, Mount Doom was the reason for his choice. Having been originally a Maiar disciple of Aulë the smith (before he decided to follow the evil Morgoth), he used the fire that welled there from the heart of the earth in his sorceries and his forging. The most famous result of his forging, and in fact the only one we know of for sure, was the One Ring.

Mount Doom was much more than just any volcano; Sauron seems to have extended his own power into it, just as his former master Melkor had extended his own power into the flesh of Arda as his means of corrupting the Valar's shaping of the world. In Sauron's case, it was probably due to his use of it as a foundry for the forging of the Ring, as he was able to control its fires. http://lotr.wikia.com/wiki/Mount_Doom

About the locations; though they're not that far apart, Barad-dûr is Sauron's 'house' and Orodruin is his 'workshop and foundry'. As a metalworker, he likely did the lion's share of the forging/metalworking and magic in Orodruin then transported the near finished hardware back to the house for a bit of polishing, detail work and to fit-up the furniture to the tree trunk as well as assemble the carriage. Throwing in a few more spells for good measure.

Both locations would have been utilized for different phases of the process but Mount Doom/Orodruin was the go-to workshop.

Answer 2

If you consider the movies canon, you couldn't get Grond into the door at Orodurin, and even in the book the lava is too far away from the floor level for convenient use in forging operations.

Since there was no other special reason to use the lava of the volcano to make a large steel object, I would say that some other location was used in Mordor.