> restart; with(plots):

fnt:= 'font = [COURIER, 12]':

> tubeplot ({[3*t^2, 2.5*t, 0.2*t, t = -4..5, radius = 4]},

  numpoints = 15,
  tubepoints = 20,
  size = [350, 350],
  axes = none,
  orientation = [-33, 69]);

> tubeplot ({[0, 0, t, t = -1..0, radius = t + 1],

           [0, 0, t, t = 0..1, radius = 1 - t]},
           view = [-1..1, -1..1, -1..1], fnt,
           axes = boxed,
           size = [350, 350],
           orientation = [33, 65],
           lightmodel = light2,
           numpoints = 10,
           tubepoints = 30);

> tubeplot ({[0, 0, t, t = -1..0, radius = t^2 + 1],

           [0, 0, t, t =  0..1, radius = 1 - t^2]},
           view = [-2..2, -2..2, -1..1],
           size = [300, 300],
           orientation = [112, 107],
           numpoints = 20,
           tubepoints = 160,
           light = [75, -30, 0.8, 0.9, 0.2],
           axes = none);

> tubeplot ({[0, cos(t), sin(2*t),

  t = 0..2*Pi,
  radius = 0.1]},
  view = [-0.1..0.1, -1.5..1.5, -1.5..1.5],
  scaling = unconstrained,
  orientation = [18, 76],
  size = [400, 400],
  numpoints = 200,
  tubepoints = 50,
  lightmodel = light2,
  axes = none);

> sphereplot ((1.3)^x*sin(y),

  x = -1..2*Pi, y = 0..Pi,
  style = hidden, fnt,
  labelfont = [Courier, 12],
  tickmarks = [4, 4, 4],
  numpoints = 2000,
  color = maroon,
  size = [400, 400],
  orientation = [-64, -113],
  axes = boxed);

> plot3d ((1.3)^x*sin(y),

  x = -2..6, y = -4..3,
  style = patchnogrid,
  numpoints = 2000,
  size = [400, 400],
  light = [75, -30, 0.7, 0.9, 0.1],
  orientation = [-129, -90],
  axes = none);