
I've made quite a few of these models before, so I can tell you that these sizes very rarely, if ever, actually match the curve size you need. make. That being said, having a sturdy round object is generally helpful for bending large parts if you want fewer wrinkles. You could probably get most of the same benefits with a durable round pin, but they're cheap and useful enough that I'd say you can buy them if you're making multiple models.

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