After finishing the piece, I export all of my Subtools individually as OBJ files which will now go back into Maya so that I can create cut lines, keys, and pin boolean objects for use in Magics. I begin by looking the model over and discerning where will be the best places to cut it based on where the easiest places are to hide the cuts in pre-existing surface features. I also balance this with where it should be cut for easiest creation of moulds. In case someone else is casting this up other than me (i.e. China) I want them to not have to redo what I've done. This eats up production time in China and drives up costs, neither of which are good things!
In Fig.07 you can see where I have created boolean objects to be used in Magics. I have created them by selecting existing edge loops and then extruding them inwards to create a surface, extracting them, then extruding them a couple of more times to create a "pie-tin" look. This allows things to fit together tightly along with aiding in the overlapping look that certain things should have, like the stockings over the legs. I'll finish the objects off by adding in wedge shapes that key the piece so it only fits correctly one way. Add in some pin booleans (standard sizes, quarter-inch, eighth-inch, etc.) and we're ready to re-export!
The resulting OBJ files need to be converted to STL files for use in Magics, so I run them through MeshLab for this process. MeshLab is freeware and an excellent tool, so for any of your mesh inspection/conversion needs, I highly recommend it!
Now that we're working in Magics, I proceed to utilise its boolean functions (unmatched among all of the software packages that I've dealt with) to cut each piece to create the final parts that will be printed. You can see some of the resulting pieces in Fig.08.
This is the final stage before print. I recheck all of my meshes in Magics to confirm that there are no potential print issues that could stop the printing process. I will also finalise the overall scale of the piece at this point. Most companies will specify the overall height of the piece, or how big the character would be standing up. I will tweak/rescale the piece to match the specs and then export all of the pieces as binary STL files.
Printing is where all of this leads to, and where you can be made or broken. You really need to be conscious of what printer you will be sending the pieces to, what that printer's resolution limit is, and what resolution your piece needs to be modelled in order to obtain maximum surface quality. I will actually go one subdivision level higher that what is visually necessary in ZBrush. This may create an insanely high polycount that is entirely out of bounds for any normal map extractions or renderings, but we're modelling for print so we want to maintain that smooth surface quality!
In this case, the printer that I had at my disposal (thanks to the guys at PCS in Timonium, MD) was the 3D Systems Invision XT - a printer that has 600x600x600 dpi resolution. It utilises two materials during print, a UV cured resin and a wax that serves as a support during the printing process that is easily melted off once the job is done.
: 3D Systems has recently released a printer with resolution nearly double that of the XT, and it's called "ProJet". I deal and have dealt with many brands and types of printers, and this one blows them all away. I've included a picture of each below (Fig.09 - 10).
After printing is done, I test fit the pieces, make any modifications to the printed models to ensure a tight fit, and go to mould. You can see the printed models in Fig.11.
Moulding, Casting & Painting
From this point, I will mould and cast the pieces in silicone and resin respectively. This first round of castings is then sanded/cleaned for recasting a tooling model. As the pieces always have some sort of build lines present, this is a necessary process for now, but as the quality of printers continue to improve, this will probably not be the case. You can see in Fig.12 an example of the torso casting along with the mould.
After the moulding/casting process, all of the parts have the sprues and flashing cleaned off and are tested for a tight fit. They are then sent out to a painter - the magnanimous Kat Sapene of WAK! Toys in this case - where the final paint job is applied. Here the models are presented in their final painted glory, both alone and at San Diego Comic Con 2008, in Fig. 13 and 14.
I hope you've enjoyed the process, if you have any more in-depth questions regarding my process or anything in particular, please feel free to contact me. I also hope it's been fun and informative!