d = 3 (slider from 1 to 5, step 1)
b = 1.8 (slider from 0 to 4, step 0.1)
c = Surface(((2 + (t * cos((d * u / 2)))) * cos(u)), ((2 + (t * cos((d * u / 2)))) * sin(u)), (t * sin((d * u / 2))), t, (-b), b, u, 0, 6.28319)
a = CurveCartesian(((2 + (b * cos((d * t / 2)))) * cos(t)), ((2 + (b * cos((d * t / 2)))) * sin(t)), (b * sin((d * t / 2))), t, 0, 6.28319)
b_1 = CurveCartesian(((2 - (b * cos((d * t / 2)))) * cos(t)), ((2 - (b * cos((d * t / 2)))) * sin(t)), ((-b) * sin((d * t / 2))), t, 0, 6.28319)