Parametric Universal Car Cup Holder Expander

Do your large mugs or tumblers wobble, rattle, or simply won’t fit in your car’s cup holder? This customizable Car Cup Holder Expander gives you the fit you need — tailor the dimensions in the parametric OpenSCAD, then print and enjoy a snug, stable holder for your favorite drink.

Features:
• Fully parametric — adjust base diameter, height, wall thickness, cup top diameter, flare angle, ribs, and cutouts for handles.
• Includes handle cut-out option for mugs with handles.
• Ribs for better grip; choose how many and depth.
• Heat-resistant materials recommended (PETG, ABS); suitable for hot interiors.
• Ready presets included: fits common travel mugs (e.g. Yeti 30oz, Stanley Classic, large insulated mugs).

The measurements and configuration starting at the bottom:  All units are MM.

• Base Diameter - Measure your car's cup holder across generally the smallest part (it might be easier if you have a removable insert and can measure that)
• Base Height - How deep is your cup holder? This doesn't need to be exact, because the transition flare will also take some height.
• Base Fillet Radius - The smaller the number the sharper the bottom edge
• Transition Flare - Nothing configured here, but the transition will be a static 45 degree angle from the bottom to the top diameter. The height will adjust automatically based on those two measurements.
• Your Cup Diameter - How big your big cup section needs to be. This will be the interior where your cup sits.
• Top Height - How high do you want the cup section to be.
• Wall Thickness - The top cups shell if you will

Options:

• Enable Cutout - Does your big cup have a big handle?  Add a cutout!
  • Cutout Height - Measured from the top of the Top Height measurement
  • Cutout Width - How wide is your handle
• Ribs (nom nom) - for easier grip
  • Rib Count - How many you want spaced across the top section 
  • Rib Width - How wide each rib is
  • Rib Depth - How deep? Don't make it too deep or it can penetrate the inside wall, or do it - its your model!
  • Rib Top/Bottom Margin - Spacing from the top and bottom edges where the ribs start and end

Finalize your model and export to your slicer, double check your measurements then print away!

I would recommend printing in PETG or temp resistant material, especially if your car tends to get too hot.

If you try it, please share a picture — I’d love to see how yours came out! Feedback welcome!