Here's an easy set of instructions to turn a single serve sunny d bottle into a funnel with 2 adjustable sizes, wide mouth and narrow mouth. I find it a quick and handy tool in the kitchen.
Step 1: Take Off Label and Wash Bottle and Top
take off the label and wash bottle and blue top
Step 2: Now Take Your Top..
now take the top and a paring knife and take the little triangle in the center out
Step 3: Before and After
Step 4: Cut the Bottom From the Top
Now use scissors or your paring knife to cut around the bottle along one of the lines along the bottle (your choice)
Step 5: You're Done
Twist the cap on and off depending on the size funnel you need.