This method is extremely flexible. Many of the materials can be interchanged, steps can be skipped or modified, and methodology bent to preference. This video is meant to give the most basic way. Use what you like and adjust what you don't.
If you don't use the jump rope method, you'll want solid stopper knots to go inside your tennis balls. I recommend using a simple over hand (for thicker rope) or an Ashley's stopper if it's a bit thinner (learn how here). If you want your handles to be a little more ergonomic, I recommend tying a figure eight on the bite.
Also, depending on the rope or cord you used, you probably want to use your tape and wrap the ends to prevent fraying. You can use a lighter to burn them too, but if your rope has any rubber in it you'll regret it (believe me, I know).
P.S.--Sorry about the subtitle colours being hard to see. Next time I'll dress better for the occasion.
1. Measure and mark rope's midpoint.
2. Cut holes in tennis balls.
3. Remove handles (or tie stopper knots)
4. Put rope ends into tennis balls.
5. Sure up the connection.
6. Cut the rope at its middle.
7. Measure and mark poi lengths.
8. Make handles.
9. Put balloons on (optional)
10. Try 'em out.
Additional notes: Bonus poi:
If you did use the jump rope method, a pair of shoestrings can turn your discarded rope handles into new travel poi. With a good amount of tape for weight they can work quite nicely.