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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
  • Airbrush
  • 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........

Step 1: Prepare your model for printing

There is a huge variety of software that a person could choose to model with - each with it's own strengths, weaknesses, and workflows.  There's some really good free software available which will work as well as some of the expensive packages.  For those interested, I'd recommend looking at programs like Wings3D, Sculptris, Blender3D, as well as many listed on this page: Free Modeling Software.

Check with the printing service you plan to use to find out the specifics regarding how they want your model prepared.  Since my original model started in a spline-based application, I definitely had to do more cleanup than someone who starts in a polygon-based app, but never-the-less you'll have to make sure your model is very well-structured to avoid getting it rejected by your printing service. In general, your model will be required to be "water tight" and have "thickness" everywhere.  While you don't have to make one contiguous mesh, you do at least need intersecting volumes that are completely enclosed.  In areas where you might have cloth or thin surfaces - like clothing, drapery - or in my case, feathers - you need to give those parts of the model "thickness" so they can actually be printed.  You will also need to make sure that any thin items meet the minimum thickness required by your printing service or the results might be too fragile to be practical.  Also keep in mind that many services charge by the volume of material used in the printing process - so taking the time to make your model a hollow shell with some thickness instead of one thick piece can save printing costs - but again - check with your print service to find out what they charge for and how to optimize your model.

Since I wanted a final product that was larger than the available print volume (8"x8"x10" in the case of 3DArttoPart)) - and I planned on making molds - I broke my model up into logical pieces and made sure the all the pieces fit inside the print volume.  I did this to make sure that I wouldn't have to pay for *two* prints to get the size I wanted.  This actually turned out to be unnecessary although it was an interesting experiment in packaging ;). 

When deciding where to break the model up, it's important to keep in mind the mold making process - taking care not to have radical draft angles or entrapment of the mold on the master part.  While it's true that just about any shape can be molded, there are small considerations a person can take early on to make life a lot easier when it comes to the mold-making and casting process.
<p>If the silicone is degassed you should not have this issue with the resin cast parts under pressure</p>
<p>Agreed. The ideal, IMO, is a properly de-gassed silicone mold, and pressure cast resin to almost completely eliminate bubbles in the casting. My purpose in this step was to show what can happen if you don't properly de-gas your silicone, and you pressure cast in that mold. It was also to show how effective pressure casting is at eliminating bubbles in the casting.</p>
<p>That's one beautiful piece of art! Looks amazing. She's bad-ass! :) Thanks for sharing the steps to your talent.</p>
<p>This instructable is a tour de force in creative and scientific mastery. I am stunned at your talent and incredible attention to detail.</p><p>...in '80s-speak: You totally rock, dude!</p><p>Thanks so much for taking the time to document and post this incredible (and awesomely successful) project. I am really, really impressed!</p><p>Cheers! </p>
Thanks, Syntegrator - it was a challenging project, but I learned a lot (which is the whole point). I'm glad you liked it :)
<p>woah you're a master!</p>
<p>I'd like to thank you for your detailed description of finishing your 3D printed figurine. For me, one of the best tips was using putty and Duplicolor filler primer. This made a huge difference in the final surface finish. Much appreciated and awesome job!</p><p>Gunter</p>
Hi Marko, <br> <br>The service I used for the &quot;print&quot; was 3DArtToPart.com - but I don't know if they're still running(?). The print, at the time, cost about $250 which was far more affordable than the $7K-$10K quotes I was getting from places that provided a better surface finish. Prices have come down and quality has gone up since that time - so you'll probably have to do a little searching around. <br> <br>There are a number of places that will print a model for you, but they seem to come and go. Protodemon.com was a place that specialized in outstanding surface quality and detail - but they seem to have disappeared. I would search for 3D Printing Services, or Rapid Prototyping Services and just check around for the best bang for the buck. A good place to ask around would be the zBrush.com forums - those guys do a lot 3D printing. Good luck! :)
HI - Awesome instructable! If I may ask, where did you have the object 3D printed and how expensive was it? I would like to follow your instructable with a smaller, less complicated 3D character and I am new to the 3D printing world. <br> <br>Thanks again for this great instructable! --Marko
Nice ! Thank you
wooow you are friking awesome!
thank you for taking the time to document this great, instructable - i learned a lot from your work, and will read this several times - Great mold making and beautifull character
My god, you have left me breathless throughout all the instructive reading. The quality that you has developed to generate all the steps to creating a perfect (why not say) molds and models, makes it can receive more than one award. To say that and from now this instructable became part of my book training (I'm not writing a book, just learning this), my sincere congratulations on the entire process of manufacturing parts, and this spectacular steep-by-steep instructive. <br>By the way my brother wants to know what is the approximate cost of the figure, in materials and paint-work, figuratively &quot;comparing it&quot; with other models that may be for sale, warcraft, mass effect, etc. ..
Thank you for the kind words :) It was a lot of work, but I learned a lot in the process. <br> <br>As far as cost of materials, there's probably somewhere around $80 in resin and another $45 or so in paint depending on what brands and colors you buy. I don't know how that compares to some of the other models for sale - but I'm assuming this would be quite a bit more since it's not mass produced. <br> <br>Thanks again - I'm glad you enjoyed the Instructable :)
Wow, this is an amazing project. The final outcome is incredible. <br>This just goes to show the large amount of skill and hard work needed to create this piece of art. Your painting skills really make this thing &quot;pop&quot;. <br>I really enjoy reading your presentation.
Where did you get your vacuum degassing machine? Never seen one like that!
I got it off eBay ;) It's a <u>Welch Chemstar 1402N Vacuum Pump</u>. It can actually &quot;boil&quot; water!
Thanks for the info!! Great instructable :) Is the chamber itself made by Chemstar too?!

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