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This Instructable covers one
process of converting a digital character model from a virtual model to a "real" world work of art. I will be covering model preparation for rapid prototyping, cleanup of the "3D print", mold making, resin casting, and final painting - I hope I can do it all justice ;)Background:
A while back, I had posted a digital render of a character I'd modeled on a popular CG (Computer Generated) art forum. One of the posters on the forum wrote that when he'd originally seen the image, he thought it was a photo of a "resin kit". At the time, I had no idea what a "resin kit" was, but after a little research I found that resin kits were pretty cool and I thought it'd be fun to make my own - having no idea what I was getting into - lol. I was also inspired by the idea of taking something virtual and making into a "real" object because as an artist who works predominantly in the digital realm, much of my "art" was not physical - it was made of bits and bytes of data - and should electricity ever go away I'd have nothing to show for years of staring into a monitor.
The obvious solution was to turn to Rapid Prototyping technology - but back "in the day" (2005) you had a choice of incredibly-expensive and nice quality, or, somewhat-less-expensive and fairly crude. I figured that crude would be OK since I wanted to learn how to make molds, had more time than money, AND I didn't want to risk messing up a $10K "print" while learning how to make molds (not that I could have paid that anyway). Today, as with all computer related technology, you can get better quality for a lot less money - but the techniques are still relevant.
At the time I started this project, there wasn't a whole lot of information available on making molds and casting resin. Yes, there was plenty of information aimed at industrial casting operations, but not much for the "guy in his garage" - so a lot of what I learned I learned by reading a lot of semi-relevant material and making mistakes. Some of them expensive mistakes. I'm going to try to point out those pitfalls so that hopefully (should you decide to blaze down this trail) you can avoid them.
Through a lot of testing, I found that there is no "right or wrong" way to make molds or cast material - just more-or-less efficient and more-or-less economical. I approached this project like a course in molding/casting and I think I learned more than I ever could have if I'd have paid someone to teach me. My goal was a very high quality polyurethane resin final product and molds that would be capable of small-scale production - and that drove a lot of my decisions (using pressure casting, buying a *real* vacuum pump, more expensive silicone etc). If a person is interested in just a one-off casting, a lot of money could be saved by using a "mother mold" system and cheaper silicone - although block molds are a lot easier for the noob mold maker ;)
Costs: To be blunt, RTV Silicone (Room Temperature Vulcanizing) isn't cheap, and neither is polyurethane resin. Costs can be reduced, again, by using "mother molds" and "slush casting" - but you will exchange your time for the savings (I won't be covering those techniques). The good news is that currently there's a lot of information available on those techniques -an internet search or YouTube search will bring up a veritable cornucopia of information. If you are looking for an even more economical way to mold/cast something, I'd suggest looking into using urethane rubber or Alginate for molds, and some of the super-hard plasters like Hydrocal to cast parts. Anyone who sells mold-making supplies can probably help you make decisions based on your goals and budget.Materials and Supplies:
What you will need depends on the materials you choose and your desired final product. For *this* project, the "core" materials and tools were:
- A digital model - followed by a Rapid Prototype or 3D print of the model
- Laquer sanding sealer
- Sandable "filler" primer
- Air Compressor - 3HP 20 Gallon model (if you are going to pressure-cast)
- Pressure pot (casting chamber - only for pressure casting)
- Vacuum Chamber
- Vacuum pump
- Various wood frames for holding molds together
- RTV silicone - I used a ShoreA 40 "clear" silicone from Shin-Etsu
- Polyurethane resin - I used a couple of different formulations from Smooth-On (different cure times and hardness)
- Silicone Spray Parting Compound
- Naptha and 90% isopropyl alcohol
- Petroleum Jelly - as a parting compound
- Sulphur-free modeling clay
- Various dental picks and waxing paddles (used during mold-making)
- A few clay sculpting tools
- Cardboard for making mold barriers
- An accurate scale for measuring silicone components
- Mixing bowls and strong mixing sticks for silicone, disposable containers for resin mixing
- Hot-glue gun and lots of glue sticks
- Packing tape
- Good quality Cyanoacrylate (CA) Glue and Zip Kicker
- Epoxy Sculpt epoxy clay or equivalent
- Various acrylic paints and laquer "dull coat"
- Various brushes, sandpaper, sponges, screens, liquid masking, painters tape, wire, gloves, etc
- Materials to build a display base (rock, wood, acrylic, glass, screws etc)
Whew! A lot of stuff for sure. Now, on to digital model preparation........