Here is the air escape version of my customizable funnel. This one is designed specifically for bottom filling molds with resin. Air can always escape even if you make a tight seal around the funnel at the mold entry point. You can make the perfect size nozzle to reach the bottom of your mold. Extract the funnel as the mold fills to reduce air bubbles. I've included several variations that you can print and use immediately. If these don't suit your needs I've also included the OpenSCAN for you to tinker with or use with Makerbot Customizer.
You can print this without support.
Set AirEscapeT to 0 for a normal funnel. Single trace spiral vase mode works for thin walled versions of the normal funnel.