Very first try at this ... whaddya think?

You're miles ahead of the competition girl for even asking opinions. Those capable of taking and useing constuctive criticism are far ahead of those that can't and don't. Probably not what you ask for but i'll tell ya what i see with my one and only "Trained" eye. The lines on the star could use a little more definition and be a little more crisp where the lines end and come together. Seems to be a surface flaw on the lower right corner of the star. I'd say blending on a smaller surface will be more difficult....for anyone. A larger format i would think would allow for the ability to achive a better/larger transition area from one color to the next. Smaller areas seem to get too busy too quick. Now keep this in mind as i'm sure you already have. Being custom, no two will be the same so yep, they could be considered a "One Off". As far as price? Custom is one price. Experiments is one price. Practice pieces is another price. With that said one is lucky if they can calculate price of labor involved/materials/consumables/burden and apply that amount to the finished product, especially on a practice piece. Sounds like you're on the cutting edge of a new concept that might turn into a lucrative skill or product so it does take some R&D. Not many folks want to pay for someone elses R&D so if you have the time/money to devote to it without compensation until you have the bugs worked out to your satifaction and those of the end user, carry on. "Practice makes perfect". Are we still friends?
Small Block