How to model the three aortic valve domes with polygons? The aortic valve consists of three sinuses of equal dimensions, in the form of dilated sacs (domes), as shown in the attached figure. The sacs have continuity with the walls of the ascending artery and form an arc. The coronary arteries originate from the right and left sacs (aortic sinuses) (see figure).
How to extrude the three aortic sinuses from a cube or cylinder in blender?
A possibility to model it is to start from the idea that half of a subdivided cube is nearly half a sphere:

From that, we can take a circle as guide, subdivide the cube and adjust vertices to conform to a third of the guide:

Once ok with it, duplicate it twice around the circle centerr:

Join them, add an edge loop at the junction, close the center. Then rip from the center in order valves to be separated:

Add a solidify modifier.

Extrude, clean the junctions to the artery:

Steps included in the file: