When I use pipe with four sides, tool always uses a circumcircle radius. Sometimes it can be uncomfortable. For example if you need a lot of square pipes with fixed side size.
The ability to change the size calculation per side/section would be a handy feature
the formula for the side of such n-gons is 2*sin(π/n)
the area of ​​n-gons is 4*sin^2(π/n)