I thought the design by Ondrasek (https://www.prusaprinters.org/prints/113421-toothpaste-squeezer) was nice, but I wanted something that wouldn't slip down or off the tube and found the corners too sharp for my liking.  So I replicated his design fairly closely and settled on this.

Should print fine without supports, etc.  It's fully symmetric, so lay either side flat.  I printed my version with 0.2mm layers.