Construct the intersection of the
cylinder
(x  0.5)^{2} + y^{2} = 0.25 and the sphere x^{2} + y^{2} + z^{2} =1. 
Construct the part of the cylinder
(x  0.5)^{2} + y^{2} = 0.25 lying inside the sphere x^{2} + y^{2} + z^{2} =1. 

Construct this model of the "icecream":  
Construct this model of the "icecream": 
Construct the portion enclosed by the
surfaces
z = x^{2} + 1/2 and z = y^{2}  1/2. 

Construct three disjoint rings each encloses the other two. 
Construct these
Borromean rings. ¡@ ¡@ 