In making the sword, we were introduced to the importance of making an object thick enough so it doesn't break. But that is not all that we need to be concerned with. The thicker the object is, the more material it requires. If the printer is charging by the material used, this can be a major consideration. I submitted the dragon to a 3D printing service several times during the building process. The initial dragon model was solid and it would have cost 224 percent as much to print as the final version where the body was hollowed out using Solidify and a well for the pen cup was created.

It also pays to shop around. Some local printers may charge you only 20 percent of what a national printer might. But they might not have the temperature controlled printer rooms and paid maintenance engineers. So, you need to see what works for you.

Blender has some tools to help you calculate the cost in the 3D Print toolbox:

If the printer's price is $1.4 per cubic cm, the sword would cost about $0.63 to print, plus a service charge for setup and so on, and shipping. If the printer charges by the area, you can check that as well.

3D printing is an art. You may have to make changes to your model or rebuild it entirely with an eye to bringing the price down. With the lunar lander in Chapter 1, Designing Objects for 3D Printing, this included steps, such as modeling all of the fuel tanks as a single unit instead of individual cylinders. This removed the extra walls in the center of all the tanks. But each cylinder also had a hole punched in the bottom, which facilitated emptying out the extra printing material, but also took less material. The landing pad was changed from a solid block and material was removed from the bottom so it was more like a soda crate turned upside down. The rocket motors were also rebuilt as hollow objects and the framework holding the motors was changed from a series of cylinders to single circles extruded along paths to make smoother objects.