I needed a quick funnel the other day & a friend asked if I was going to share the info (which means put it up on the blog). So I did a quick recreation to tie into a couple pics I took at the time.
You can use any size cup, just roll it small or big to fit the container you want it to fit into. Cut around the bottom, & roll. You can also use a paper plate in a pinch, but really, a funnel is useful too ;}).
BTW, ‘aim’ for the center hole.