Caro Marchetto:you are learning Moi right?so please avoid these sharp corners or weird surfaces that suddendly change direction like these













I tried this way:first i copy all side edges,rebuild to have less seams and mirror,then made a loft to get the chair
so i made few modifications to give a better smooth curvature deleting these surface and did Blend G2 using different bulge values





Now yellow and red edges used to sweep or network to get the cap




That's all i can do,forget to fillet or do Mike's method(sweeping circleson side edges+trim+blend) surface still too complicate

M