http://pappathan.net/tutorial/c4dpumpk2/pumpko_project1.htm
Methods of Madness : Projecting Splines onto a Radial Surface

Pumpkinitis Part 2


This assumes you've read the previous tutorial, Linear Lofts and Pumpkins here:
http://pappathan.net/tutorial/c4dpumpk/cheapo_pumpkin.htm
...and then what to do once you have to make cutouts needed for a face...

If you haven't, simply drop in a sphere primitive  and follow along.
Grid and Point Snap on.

1. In XY [front] View draw the B-Splines needed for the eyes. 
Menu: Objects > Create Spline
Draw one eye and copy\paste for the other - rotate 180 on H  (X Axis) .
Move each 'eye' an equal distance from the Y center line. .eg. -100 and +100 on X.

The nose is a simple n-Side.
Menu: Objects > Spline Primitive > n-Side
Attributes, 3 sides - Rotate 30 on Z Axis.

The mouth is another B-Spline with points added for more shape control.
Menu: Structure > Add Points.


Note : The splines will all be at dead center

2. In the Object Manager Shift + Left Click to select all 4 splines.
In the screen cap I've named mine...
Menu: Objects > Connect
This groups the splines and makes them a single new entry in the Object Manager.

2.a 
Important! As I mentioned the splines are at the object center. 
If they are projected now what you see is not nearly what you will get or want.
Using Top View, Move the face profile group out to the front of the pumpkin as shown.
One grid line in front on Z is fine. You will still be able to adjust the spliney face if needed.

3. Return to Front View.
Because you are projecting onto a round surface the vertical center is a bit too low.
Move the group up on Y, this will be trial and error until you get the projection you want.
The easiest way to fix it is after projection. So project away.
Menu : Structure > Edit Spline > Project...
Select Radial from the selection list and hit OK.
You should have something lika dis:


4. Extrude the cutouts - still in Front View.
Menu: Objects > NURBS > Extrude NURBS
In Extrude Attributes [Shift + F5 ]  Movement (depth of the extrusion) in Z must be enough to cut through the pumpkin body.
<img>
Use -Z in Coordinates to 'pull' the extrusion forward.
<img>
The result should be similar to this image (I'm using X-Ray mode to make the body semi-transparent):
<img>


5. Boolean subtract the extrude object from the body.
Menu: Objects > Modeling > Boolean
This puts a Boole at the top of the object list.
Select the Extrude NURBS.1 in the Object Manager and Make Editable (C Key).
You may want to Object > Connect the NURBS and Caps...up to you.

The properties I used for the Boolean object are;
Type: A Subtract B (A being the first item below the Boole)
High Quality
Hide New Edges
Create Phong breaks at intersections
<img>
Drag the face shape, then the pumpkin body onto the Boole.
<img>

6. Save the Project file
Add mats, lights. Render...
<img>

If you want to export as 3ds or obj delete all but the Boolean object and save using a NEW NAME.
I have the project file should anyone need to take a look - it includes all items from step 1 to the end.
120Kb zip here.

Next up UV mapping and Texturing.

Best regards,

Pinhead
4/16/2007
C4D ver 8.5 was used for this tutorial but spline use is generally standard.