Printing a three dimensional object about a preformed structure

1. A method, comprising:

obtaining a data file that includes print instructions for causing a three dimensional printer to print a three dimensional object, wherein the data file describes external surfaces of the object;

providing user instructions for positioning a preformed structure so that the three dimensional printer can print the object around the preformed structure, wherein the preformed structure has a size and a shape to be subsumed within the external surfaces of the object;

modifying the print instructions so that the printer will print the object around the preformed structure; and

printing material around the preformed structure using the modified print instructions to form the object.

2. The method of claim 1 , wherein printing material around the preformed structure reduces the amount of time required for the three-dimensional printer to form the object.

3. The method of claim 1 , wherein the user instructions are provided in response to determining that a remaining amount of print material available to form the object is less than required to form the object, or determining that the amount of time required to form the object is greater than a time setpoint.

4. The method of claim 1 , further comprising:

maintaining data describing an inventory of preformed structures that are available to be positioned in the three dimensional printer; and

selecting one of the preformed structures from the inventory to be the preformed structure that is positioned into the three dimensional printer by identifying, using the data, that the preformed structure has a size that can be subsumed within the object.

5. The method of claim 4 , wherein the preformed structure was previously printed on the three dimensional printer.

6. The method of claim 5 , wherein the preformed structure that was previously printed on the three dimensional printer is defective.

7. The method of claim 1 , wherein the user instructions include dimensions for user selection of a preformed structure that can be subsumed into the object.

8. The method of claim 1 , wherein the user instructions identify a position for placement of the preformed structure.

9. The method of claim 1 , wherein the user instructions are output to a display screen and include an illustration of a desired position for the preformed structure.

10. The method of claim 1 , wherein modifying the print instructions for printing the object to account for the preformed structure includes printing around the preformed structure.

11. The method of claim 1 , wherein modifying the print instructions so that the printer will print the object around the preformed structure includes providing print instructions for forming an internal void in one portion of the object in response to positioning the preformed structure in another portion of the object.

12. The method of claim 1 , wherein modifying the print instructions so that the printer will print the object around the preformed structure includes leaving voids in a portion of the object to offset additional weight of the preformed structure.

13. The method of claim 1 , wherein the preformed structure has a predetermined size and shape, and wherein the data file includes modified print instructions to account for presence of the preformed structure.

14. The method of claim 1 , further comprising:

scanning the preformed structure after positioning the preformed structure in the three-dimensional printer to determine the actual positioning of the preformed structure, wherein printing material around the preformed structure to form the object includes modifying control of the three-dimensional printer to adjust to the positioning of the preformed structure.

15. The method of claim 1 , wherein printing material onto the preformed structure includes printing material onto upward-facing and side-facing surfaces of the preformed structure.

16. The method of claim 1 , wherein printing material onto the preformed structure includes printing material onto surfaces of the preformed structure until the preformed structure is subsumed within the interior of the object.

17. The method of claim 1 , wherein the preformed structure is selected so that the object will have at least a minimum depth of printed material around the preformed structure.

18. The method of claim 1 , further comprising:

printing a base portion of the object prior to positioning the preformed structure into the three-dimensional printer on the base portion; and

continuing to print the object after positioning the preformed structure into the three-dimensional printer on the base portion.

19. The method of claim 1 , wherein the size and the shape of the preformed structure are random.