I’ve tried several of them and the only one that really works for me is the Clover brand one. The others, in my opinion, are no better than the cardboard method. Joann’s carries the Clover one (www.joann.com) .
I second Yarnrainbow’s suggestion. I have the Clover size small set, it is veritably simple to use and my pom-poms have turned out full and uniform in size with minor shaping. There is another thread (from January or February) that touched on this topic of pompom makers or making pompoms. If you do a search I’m pretty sure you could find it and get some other ideas and opinions.
Katrina