A funnel
thingiverse
The thing you're talking about is an actual tool called a funnel - one of the most fundamental gadgets people use on a regular basis without even realizing it's truly as ordinary and uncomplicated as that - a tool with just one specific function that we commonly associate with our daily lives.
Download Model from thingiverse
With this file you will be able to print A funnel with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on A funnel.