On May 5 I sent through the list my previous message regarding this thread. In it, I told you I decided to contact the creator (Víctor M. Nuñez) of the prior model ("Star bowl"), and discuss with him if my model was a variation of his own or not.
So I thought about sharing the highlights of the conversation with you guys through this new message. Maybe it can help others that are also uncertain about declaring their model an original creation or a variation, or even a development in the sense that David Mitchell explained. In my message I told Víctor about my box and how it came into existence by tinkering with his bowl. Being that the case, I proposed him to consider the box a development and that we should credit ourselves as co-creators of the box. My argument was that the box wouldn't have existed without his work on his bowl but it wouldn't have existed either without my own effort over his bowl. I didn't told him this but I considered the case of the box a similar one to the novel "Pride and Prejudice and Zombies" which is credited as being co-authored by Jane Austen and Seth Graham-Smith. Seth created his work using as raw material Jane Austen's "Pride and Prejudice". Any way, some time later I received Víctor's answer. He told me to consider my model as my own original creation and to just mention his bowl as inspiration. I simply answered him that, although I didn't agree I would respected his proposal. So the box is now my latest creation and, being the case, I've taken the pleasure of naming it: "Curved Box with Blades. I just love descriptive names. That's it. Thank you all for sharing your thoughts about variations in origami. I'm also really thankful with Jeremy Shafer who wrote the article that gave me a new perspective on this subject as I had told you in my last message.