[RickM]

Wow, there's alot to cover. Emachine shop will take the specs you provide and translate into a machined piece. My experience has been best when working with someone locally and providing very frequent feedback to develop the prototype properly.

Will you need to source other components for this idea?

Things to keep in mind when maturing the design are :

-Can this be manufactured efficiently?
-Replicated cost effectively?
-Can I utilize alternate materials if needed?
-How many steps will be required to assemble?
-How will this product ship? (weight and/or size an issue?)
-Can it be copied too easily? (Brand identity very important)
-Any obvious liability/safety concerns?
-Are you designing to last forever? Does it need to be?
-Turn around time for each component?
-Can this be manufactured and shipped from overseas reliably?

A good design is a simple design....Keep it simple stupid.

Then you have a multitude of legal protection concerns such as Copyright, Trademark, Patent(s), Liability insurance, etc.

Marketing can be a bit easier these days with the internet but you'll need a plan to determine timing, saturation, ordering frequency/volume, target audience and intelligence gathering (JD Powers/Polk etc), budget etc.

I love and have done the full cycle a few times and am passionate about it. Each step is quite interesting.