You ask if we think this is good enough to be marketed.
Three things:
- The practicality issue, but you've already adressed that in other posts.
- DO RESEARCH! There have been a lot of releases lately of 'old, but forgotten or revamped' principles, which turned out to be either crap or someone else's work. Contact some knowledgeable people, have them look at it (yes, method too), so you might find out about any similar ideas. Even though you may not have used them for inspiration, it'd still be nice. And should the exact same idea already have been published, then congrats on thinking it up yourself!
- Third, a general statement. In the last few months, a slew of products has hit or almost hit the market by several kids (by that I mean 14 or 15 year olds). One did it just to get some attention, then wisely decided to back down.
Another, who goes by the name of Dan Army (gentlemen, start your search engines) has released several items and is now widely disliked (I'll keep it clean).
This is not a statement against young people coming up with their own stuff, rather an advice FOR them. Keep it to yourself, what's the rush? Let it soak, grow and develop, come up with more ideas, nurture your creativity. Rushing to get your name 'out there' isn;t always a good thing.