To be honest those look quite similar to barbell weights, but isn’t a bold the object peeking in the bottom right of the picture? Is that a giant bolt?
Probably the actual barbell.
In addition to that, what is the oven story?
He probably had to heat the tools to be able to dent the barbell weights' surface. But I'd really like to see how the words look like; even if it's a single letter.