Center cylinder around complex object

Dear all, I have a complex object (aortic root) and I would like to center a cilinder around it. In real life application, the cylinder would mimic a pitcher within which the 3D printer model of the aortic root would be placed.
Would you please suggest how to do so?
Thank you.

Why not just make the cylinder as a separate object and the move it into place? You’ve already done all the hard work, so adding a cylinder should be a piece of cake.

First of all, thank you for the hint.

However, my main issue is how to place the cylinder perfectly simmetrically around my aortic arc. The same way it happens when I placed the 3D-printed arc into my pitcher (that suprprisingly has the right diameter).

You could try projecting the object onto a plane, drawing a line between the outermost opposing points, and drawing a circle at the midpoint of that line. Then just extrude the circle.

this sounds like a very good idea. Thank you.
However, while trying to project it, I realized my model is in STL as it comes from a CT scan and does not allow me to project it.

You’ll need to use something like Fusion 360 to convert the mesh to a solid body.