Shell a lofted entity

Hi all, I try to shell this part (please see attachment "new_head.SLDPRT"), which is a lofted entity.

I want to shell it with thickness 3mm, the cross-section profile looks like this.

But apparently it's not gonna work. Caused by the thickness is greater than the maximum curvature. I don't know what to do to deal with that. Please help, thanks!

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