3D-printed Gray Resin

Frequently asked questions.

Please keep Model Monkey products away from young children and pets.

3D-printed models can pose a choking hazard.

3D-printed models require special tools, glues and techniques. Therefore, our models are recommended

only for very experienced modelers.

What is 3D-printed gray resin? Gray resin is an acrylate-based plastic chemically similar to Plexiglas requiring special techniques and tools for best results. Gray resin is chemically different than polystyrene plastic found in injection-molded plastic kits. Although gray resin is more fragile and brittle than polystyrene, gray resin captures much better detail. Here are some Model Monkey products 3D-printed in gray resin:

How do you make the models? 3D-printed models are not cast inside a mold. Our grey resin models are produced using 3D-printing technology inside a machine. We use two different kinds of 3D printers, SLA (stereolithography) and LCD (liquid crystal display). Both kinds use ultraviolet light to harden liquid resin. Our SLA 3D-printers use a laser. Our LCD 3D-printers use a light screen similar to that in your cell phone. Click here to watch a video of a Form 3 SLA printer in action. Models made from SLA and LCD printers look the same but the "raft" is different and resin color varies from light gray to dark blue-gray. The "raft" is the tray supporting the models.

How long does it take for the 3D printer to make my models? 3D-printing models one layer at a time is a very slow process. Typically, it takes several hours to print a single model. Large models and large orders for many models can take much longer to print. Thank you for your patience!

Why does the model have so many supports? Each gray resin model will come to you with several supports attached to it. These supports look like "sprues" found in injection-molded plastic model kits. Since 3D-printed models are not made inside a mold like injection-molded plastic kits or other resin models, there is no mold to provide support to overhanging features during printing. Without a mold, overhanging features must be supported in some other way. The 3D printers we use create supporting "sprues" which rise up from a tray called a "printing raft" to support overhanging features during printing. The models cannot be 3D-printed without the supporting sprues and printing raft. Sprues and the printing raft also provide strength to the model during shipping. Sprues and the printing raft must be removed by the modeler. Support removal is normally difficult. That's why 3D-printed models are recommended only for very advanced modelers, not beginners.

Do 3D-printed models have print lines or pinholes? Tiny voids called "pin holes" in the uppermost layers, and faint print lines on surfaces, are normal characteristics of 3D-printing technology and may be present in the models you receive. We use the best 3D-printing technologies available to minimize any print lines or pin holes in models. Layers may be visible but normally disappear under paint. Small pin holes can occur in the upper layers when the normal mechanical operation of the 3D printer causes tiny bubbles to form in the resin during printing. Pin holes can be filled with paint or putty by the modeler.

Should I be concerned if a printing raft arrives damaged? Normally, no. When printing is complete, we use significant force to remove the model from our 3D printer's "build platform". Occasionally, significant force can damage the printing raft. Slightly damaged rafts are a normal characteristic of the production process we use. Printing rafts are intended to be discarded. If the raft is damaged but the model is intact, we consider the model successfully printed and will ship the model to the customer.

Why do you print models at an angle? Printing larger models at an angle helps prevent sag from occurring between supporting sprues during printing and makes sprue removal easier.

How should I cut away the supports?

Most importantly, work slowly. Rushed efforts can damage models.
Attachment points are smaller in diameter than the supporting sprue. The attachment points' diameter varies between 0.3 mm and 0.6 mm. Attachment points are normally weak.
Use a very sharp cutting tool like the electric hot knife, Xuron photo-etch scissors, or sprue nippers shown below. Do not use a common scissors. Common scissors tend to twist while cutting and can damage the model. Your cutting tool must be very sharp so that you don't have to force the cut. The old saying, "let the tool do the work" applies. Heating the blade may help.

Try not to twist, push or pull when cutting. For small models, place the tool in a good position to cut nearest the part, not the printing raft. Try to make the cut so that you do not have to move the tool or the model when cutting.
Large, hollow models like turrets, boxy fire control directors and pilot houses will have many internal supports that may be difficult to reach. Cut the supports nearest the printing raft first. Start at the outside, working your way around the model. Work inwards, carefully cutting away the printing raft. Then cut the supports from the model.
Make final cuts near the attachment point. Try not to twist, pull or push when cutting.
Gently trim or sand away any remaining "nubs" just like you would on models made from injection-molded polystyrene plastic.

If you accidentally break off a piece of your model, you can probably re-attach it using CA glue. Gray resin is brittle. Resin plastic does not bend, so the break itself is not likely to be deformed.

How should I clean the model? If you need to clean your 3D-printed model, a cotton swab dipped in isopropyl alcohol ("rubbing alcohol") is recommended. You can also use warm water with mild dishwashing liquid like "Dawn", "Fairy", "Joy", "Simple Green" or baby shampoo (no conditioner). 3D-printed gray resin plastic is chemically related to Plexiglas. Cleaners that harm Plexiglas can damage gray resin, too. Do NOT use acetone or acetate (fingernail polish remover) to clean your models. Acetone and acetate can melt 3D-printed plastic.

Does your 3D printing process use waxy support material or oil? No, our 3D printers do not use waxy support material during printing. No oil or other mold release agent is used. No cleaning away any wax, oil or mold release agent is necessary.

Do gray resin models come fully hardened? Normally, yes. No additional exposure to ultraviolet (UV) light, called "post-curing", is needed. Your model is created when ultraviolet light emitted from a laser or LCD screen chemically hardens liquid resin. After printing and cleaning, we place your gray resin model in a heated UV light booth to fully harden the resin before we ship your model to you. If you find a spot on your model that feels a bit rubbery, place the model in direct sunlight for a half hour or so, exposing that spot to the sun's UV light. The sun's UV light should finish hardening that spot.

Do you send assembly instructions with the model? Normally, no. Most models are direct replacements for plastic kit parts so your plastic kit's instructions are applicable. Please study photos and renderings on the product webpage. For the most complex Model Monkey products such as 1/32 scale Bristol Beaufighter cockpits, multi-part ship superstructures, and 1/24 scale P-51 Mustang wheel wells, painting and assembly guides are available for free download from this catalog.

What kind of glue should I use? Cyanoacrylate (CA) "super glue" works best. For larger parts, epoxy can be used. Generally, glues that work well with Plexiglas will work well with gray resin. Liquid glues intended for injection-molded polystyrene plastic models, such as "Testors Liquid Cement" or "Tamiya Liquid Cement", may not work with gray resin. Superglue remover containing acetone may harm the plastic.

What kind of paint should I use? Gray resin plastic is compatible with many common acrylic, enamel, and metallic (Alclad 2) hobby paints without the need for primer. Gray resin also accepts Molotow marker paint for painting tiny details.

Since glue and paint composition varies by manufacturer, you may wish to test your glue or paint's compatibility with gray resin. Test your glue or paint on your 3D model's "printing raft". Remove your model from the raft. To test your paint, paint the smooth raft bottom without primer. Check your results and proceed accordingly. Do not use methyl ethyl ketone "MEK" as an airbrush paint thinner. MEK is known to chemically react with 3D-printed plastics. MEK can produce a powdery residue on top of the paint that is difficult to remove.

Which technique works best to paint narrow walkways and platforms on small, one-piece superstructure models like aircraft carrier islands?

Airbrush the whole model the color of the bulkheads, for example, "Light Ghost Gray" or other bulkhead color paint. Let the paint dry.
Then with very diluted deck color paint, such as "Gunship Gray" or other deck color, touch the ends of the catwalks and platforms with the tip of a small paintbrush and let capillary action and gravity draw the watery deck color paint along the catwalks and platforms. Let it dry. Repeat, if necessary, until the desired opacity is achieved.
After the deck color paint dries, touch up with your bulkhead color paint as needed with a very fine tip brush.

Are Model Monkey gray resin models made by Shapeways? No, our gray resin models are not printed by Shapeways. Some Model Monkey designs, like metal and plastic nameplates and models too big for our printers, are not suitable for gray resin printing. We make the models that aren't suitable for our own 3D printers available from another 3D printing company called "Shapeways". Shapeways uses various 3D printing technologies better suited for very large models and metal objects. Models and nameplates ordered from Shapeways are sold, printed and shipped by Shapeways from their factories in New York and The Netherlands. Click here to see Shapeways' website and learn more about Shapeways' materials and their cost.

I bought some models of your design printed by another company called "Shapeways" in a white plastic material. How should I prepare Shapeways' white plastic for painting? Shapeways' white acrylic "Smooth Detail" plastic is chemically different from Model Monkey gray resin and requires different preparation. Shapeways' white acrylic plastic models are printed using a different process than our Model Monkey gray resin models.

Keep your Shapeways models in their plastic wrapping until you are ready to paint them. Shapeways' white acrylic plastic may be harmed by prolonged oxygen exposure.
Unlike gray resin, Shapeways' white acrylic plastic 3D-printing process uses wax during printing and warm oil to clean the model of wax after printing. Clean any residual wax and oil from Shapeways' white acrylic plastic with isopropyl alcohol or warm water with mild dishwashing liquid like "Dawn", "Fairy", "Joy", "Simple Green" or baby shampoo (no conditioner). Cleaners that harm Plexiglas can damage Shapeways' plastic too. Do NOT use acetone or acetate (fingernail polish remover) to clean your Shapeways models. Acetone and acetate can melt 3D-printed plastic.
Place your Shapeways white acrylic plastic models in direct sunlight or under another ultraviolet light source for a half hour or so to ensure all of the plastic is fully hardened. Enamel paint may not harden on Shapeways' white acrylic plastic if the plastic itself is not fully hardened. Fully hardened Shapeways acrylic plastic is translucent white, not yellow, and has little or no odor. If your model is yellow or has a strong odor, uncured resin is present.
Acrylic primer and acrylic paint for plastic models work best with Shapeways' white acrylic plastic. You can use enamel paint but the white acrylic plastic must be fully hardened before painting.
Cyanoacrylate "CA" glue works best with Shapeways' acrylic plastic. Epoxy works, too, as well as other adhesives intended for Plexiglas.
Do not use methyl ethyl ketone (MEK) as a paint thinner for airbrushing Shapeways' plastic. MEK is known to cause a white, powdery residue to form over the paint after the paint has dried. The residue is a nuisance to remove.
An "air eraser" may be helpful in smoothing Shapeways' plastic surfaces. Air erasers are typically used to etch glass and other surfaces. An air eraser looks like an airbrush but costs much less. An air eraser emits grit rather than paint. Modelers use common household baking soda as the grit. Baking soda is inexpensive, plentiful and non-toxic. With careful use, baking soda is generally soft enough not to damage the model but hard enough to smooth surfaces. Using an air eraser is also helpful in cleaning models and removing unwanted paint without damaging the model. Here is one example of inexpensive air eraser:

Will you send me a free sample? Model Monkey does not honor requests for free models. Model Monkey provides complimentary review samples to professional, public scale modeling websites we sponsor.

Will you research and design a model for me? Model Monkey is not able to provide research and design services to individual modelers. You can hire other professional 3D designers from sites like Shapeways (click here).

Will you alter the design of an existing model for me? Model Monkey is not able to provide custom alteration services to individual modelers.

How are your models designed? All Model Monkey designs are original and proprietary, created one line and shape at a time using sophisticated Autodesk CAD software on a powerful computer. Our models are not copies of any plastic, resin, wood or paper models' kit parts. Nor do we steal files from computer games, such as "World of Warships" and "World of Tanks", and adapt the stolen files for 3D-printing. Occasionally, we are licensed to sell a model designed by another talented designer. The original designer maintains the copyright of those models.

I have my own 3D printer. Can I buy your *.stl files? No. The computer aided design *.stl files used to print Model Monkey products are proprietary and are not for sale.

I have my own 3D design. Will you print it for me? Model Monkey is not able to provide printing services.

I have my own *.stl file. You can have it for your store if you send me free models printed from my *.stl file. No, thank you.

Will you send me the references you used to design your models like high-resolution photos and 2D plans? No.

Can I buy one of your models and make copies of it, even if it's just for my own use? Legally, no. Model Monkey-designed models are legally considered "creative works" of Model Monkey LLC and are fully protected by US and international copyright laws. Although you own the model, Model Monkey LLC continues to hold the copyright of that model. Making copies of models we designed, even for your own use, infringes upon our copyright and is illegal. Copying our models deprives of us of the revenue we earned in researching, designing and making the model. Our "creative works" include:

Model Monkey-designed models and nameplates
Model Monkey-designed models and nameplates 3D-printed by others, e.g., Shapeways
CAD files used to print our models and nameplates
this catalog
photographs we made of our models
computer generated renderings we made of our models
painting and assembly guides we produce

Can I buy one of your models, modify it and sell copies? Legally, no. Modifying our models then selling copies does not meet the legal requirements associated with "derivative work" or "fair use" under US and international copyright laws.