My old design was popular, and several people sold prints of the design through their Etsy and similar online stores. However, it was annoying having to keep track of the different inserts for varying drink sizes. Taking design cues from the stock cup holders, I designed a new version that requires a bit of 3D Printing trickery.

Print the Insert piece first in a flexible filament (TPU, TPE, PEBA, etc). Then, when you print the main cup holder part, you can place a print pause at the layer before the insert cavity gets enclosed. Place the printed insert into the cavity and resume the main print. The insert gets trapped inside the cup holder and serves as an adjustable sizing piece for different drinks.

Since the cup holder will be in a car that can get hot in direct sun, print the cup holder out of ABS or ASA for best results.