If you're anything like me, you like the KISS methodology. Ladies' urinals don't get less complicated or more practical than this.
Matter of fact, I think the pictures pretty much speak for themselves but here goes anyway.
You need one empty plastic water or pop bottle
Use your knife to start the initial cut in the plastic. Cut downward toward the base.
Use the scissors to cut a largish egg shaped opening on a slight diagonal.
Fold small strips of duct tape over the cut edges to cover completely. When you tape around a curve, cut the tape so it folds in easily.
Leave the outer wrapper intact so it's more discreet.
This can be rinsed out and reused.
Be happy if you have male plumbing, or one of these if you don't.