Cartolio, I have a few questions and comments, but first I will try to answer your questions.
1. I don't know. It would depend on whether or not I had a door that could really use it. On an exterior door, probably "no" because it might interfere and in some cases, I have issues with my doors dragging on the floor because the floor is not level, so any additional thing that might catch on the floor can be problematic. For interior doors, I think it could be a "yes" as there are a few places in my home where I could use something like this where I don't want to have an ugly stopper on the wall and my interior doors are flimsy hollow core so it would not be easy to screw something on that wouldn't just punch a hole in the door.
2. Yes, it doesn't look like it has any means to stay on the door without sliding or moving around, from the 3D model, the bottom is far too thick, and it would be rather unsightly to go up that far on both sides of the door. You may want to consider rust-proof metal versions as well as plastic for people who don't like plastic.
3. I am guessing the term "elevator pitch" is to elevate interest in the potential product? If so, its ok, but I've not seen many professional pitches to really be able to judge. I think you would need to make sure your grammar was correct. For instance, question 2 should have read "Are there any design flaws". You should perhaps incorporate more details about the product, what its made of, how it fits together, what benefits it would have over other stoppers, etc.
4. I'm not sure on names. I'm pretty terrible at coming up with names for things. Slip-on-stopper? Clip-on-Stopper? Easy-door-stop?
Now, on to the questions:
1. What are the dimensions of this stopper?
2. Is it adjustable to fit different door sizes, or would people need to get a specific one for a specific depth door?
3. How far out does the stopper extend from the door?
4. Do you have more details about the rod that comes out with the stopper? Is it a spring that can bend? (from the picture it looks like a solid rod, and I would think that might work like a ramming rod)
5. What makes this a better choice than one of those little rubber things you can stick on your wall to catch the doorknob?
6. Will this come in different colors/finishes?
7. What will make this stay in place (as beachguy asked)?
some comments:
1. It would be nice to see a picture of this as placed on a door to show how large it is in comparison tot he door and if it would interfere the the look or design of a door.
2. I'm not sure people would like to have something that is visible on both sides of the door-- especially if they have a nice-looking door.
3. Maybe there would be a way to make it not go up as high on the other side of the door but have the other side at a slight angle so it sort of clamps down on the door but has something to prevent it from damaging the finish.. Kind of like some plastic binder clips...
I did a couple of very rough sketches.
So, there could be a tiny little lip that you could fit your thumb on to pull it back to make it loose so you could pull it off but when the lip is not pulled on it would exert enough pressure on the door to hold it in place without sliding. It would be low profile so it wouldn't be as obvious on the exterior part of the door.
Another method of holding it on to the door would be to put magnets strong enough to pull at each other to hold it on. But that might have issues with doors of different densities. If you made the lip large enough that someone could hook their toes on to it, they could conceivably put their toes on it and exert a little pressure to be able to slide it with their foot to remove it when they want to take it off (this would be done when the door is open).
4. The plastic would have to be strong enough to not break easily.
And I just got interrupted and now can't remember my other thoughts. But, those are just some things to think about.
One additional thing is that you should check the site that lists patents for things and make sure that this idea is not already taken.
Edit: You might have to make both sides have the little part that pinches near the bottom to keep it from sliding, but I don't know. Its something you would have to play with as a prototype.