Tony gives some excellent advice. Unforseen expenses pop up all over the place. You run out of sandpaper and have to make a special trip to buy more. Your plans printing service increases their printing prices, You have to buy small business software and take the time to learn how to run it. The place where you were buying boxes suddenly discontinues the size box you need.

I recently started selling laser cut short kits for one of my own 1/2A designs. The cost of the balsa wood and the laser cutting together are less than half the total cost involved in getting a kit shipped out with plans, instructions, packaging, shipping costs, materials, my time and a meager profit. Whatever it costs you to actually produce a fiberglass fuselage is only going to be a fraction of the total cost of getting the finished product delivered to the customer.

I'm not saying don't do it. But, I would do a test run before promising anyone a price.