Below are a few tips to consider in designing parts with bends.
Provide for allowance – it is better for pieces to be a bit loose than to
not fit at all.
For two-part enclosures it is generally advisable to add at least some overhang.
To specify the general radius of bends choose Job | Settings | Specifications: Bend.
You can specify helical twists.
You can approximate a model of a curved sheet or a large radius bend by making several parallel bends, each of a small angle.