Customized Cup Holder Adapter for SodaStream, Coffee Cup & Water Bottles. I Made in at TechShop.

Problems
       Different cars have different size cup & bottle holders.  Drivers and passengers have different size of their favorite coffee cups and bottles.  When your vehicle bottle and cup holders don't don't match your favorite coffee cups and bottles, what can you do?  Who do you gonna call?  
       When the cup holder is too small, the bottle simply won't fit.  Many cup holders could not hold Soda Stream bottle.  In this case, a cup holder adapter could help.     Some water bottle are skinny and these won't fit the cup holder snagly.  In this case, a cup holder down size adapter could help.

Solution:
       You could always customize a cup holder adapter to fit larger or small cup or bottle.   Just make sure that your design is feasible.   Test it in a parking lot before using it on the road.  Fill the cup or bottle to full.   Subject it to abrupt go and stop.  Make sure no surprises would occur.  Be extra careful when deal with very hot or very cold liquid or large amount of liquid.

Goal:
     To make a couple of sample cup holder adapters. One made for up sizing and one made for downsizing.    The design won't be optimized.  It would just be an illustration of the basic idea.   Members who have access to 3D Printer are encourage to make custom design or improve on current designs and contribute.

Design Consideration:
    The Autodesk Inventor file is made scalable so it could be quickly adjusted to varying condition.
    The wall thickness of the cup holder adapter is currently set at 2mm.
    The outside diameter of the lower portion is a critical dimension, It is the diameter of the existing cup holder.
    The inside diameter of the upper portion is also a critical dimension.  It is the diameter of the bottle which is too large to fit existing cup holder.   In this example, the bottle is a Soda Stream Bottle (7-3/4" tall).
    The depth of the lower portion match the depth of the existing cup holder.
    The depth of the upper portion is made equal to the height of the center of gravity when bottle if full.  This need to be designed and tested so that bottle or cup won't tip during abrupt acceleration and deceleration.
    A small screw hole is located at the bottom to fasten the cup holder adapter dow firmly.

CAD Procedure:
    * Draw the half section in 1 single line.
    * Use offset to create a thickness.
    * Edit the Sketch section.  Use Sketch Doctor to make Close Loop.
    * Make a reference draft angle.  You can tune this from 0 deg (when 3D Printing) to 1-2 deg when creating inject molding die.
    * I used parametric modeling.  4 critical parameters. (1) Outside Diameter of lower part (2) Inside Diameter of higher part.  (3) Depth of power part and (4) Depth of higher part.   Test the parametric model by varying these 4 parameter and check if the model is updating accordingly.
    * On 2D Sketch, add fillets on corners.
    * Exit 2D Sketch.  Enter 3D Model.   
    * Select Revolve,  Full 360 deg.
    * Save File.
    * Export STL.  At TechShop, we save on a thumb drive and move to the computer with the MakerBot 3D Printer.
    * Exit Autodesk Inventor.

Results:
     I was unable to print my original design.  Since the based area is too small to build up the bottom of the cup.  It would warp and I was not using rafter.   The new MakerBot software has improved a lot.  I was not using rafter then.  I am experimenting with alternate way to support the base to the platform (see new photo).
     The other problem is at the transition area is not 3D printable since it got horizontal overhanging section.  This would require using support.  I change this to 45-deg slope transition.  With 45-deg slope, we could print without use of support.