[Ron Wood]

Just as an afterthought, at $2.5K I do not think it would be unreasonable to stipulate exclusive rights to the blueprints/measured drawings. That way you would eliminate competition unless you further licensed the drawings, and if for some reason you could not go into production you could recoup your investment in the drawings if someone else wished to take up the project.
If you really want to attract potential buyers, you need to establish a price point for the three variations. This will require realistic estimation of production costs and realistic production time. Investors need to have some assurance they will be guarenteed a gun as specified in a timely manner. I think a two to three year lead for production is reasonable. To be informed after two years on a waiting list that it will be another two years until delivery would not be a good marketing practice.