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3D-printed Gray Resin

Things You Need to Know

Model Monkey products can pose a choking hazard to young children and pets. 


3D-printed models are recommended only for very experienced modelers, age 12 and up.

Model Monkey products ordered through this catalog are 3D-printed by Model Monkey in North Carolina, USA, in opaque, gray resin plastic capturing very fine detail.  Surfaces are very smooth. 


Gray resin is an acrylate-based plastic, chemically similar to Plexiglas.  Gray resin is not nylon.  Grey resin models are produced using a different technology than that used by other 3D-printing companies like Shapeways.  Gray resin is chemically different than polystyrene plastic found in injection-molded plastic kits.   Gray resin is also more brittle than polystyrene.  Here are some Model Monkey products 3D-printed in gray resin:


Production time. 3D-printed models are not cast inside a mold,  3D-printed models are created in very thin layers one layer at a time.  This makes 3D-printing a very slow process.  Typically, it takes several hours to print a single model.  We print models after an order is placed, on a "first come, first served" basis.  We will print your model as soon as any orders received previously are complete.  Thank you for your understanding and patience!

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 sprues to support overhanging features during printing.  The models cannot be 3D-printed without the sprues.  The sprues also provide strength to the model during shipping.  Sprues must be removed by the modeler.  Sprue removal is normally difficult.  That's why 3D-printed models are recommended only for advanced modelers, not beginners.    


Support Cutting Advice. 

  1. Most importantly, take your time.  A rushed job can lead to damaged parts. 

  2. Attachment points are smaller in diameter than the sprue.  The attachment points' diameter varies between 0.35 mm and 0.6 mm.  The attachment points are normally weak. 

  3. Use a very sharp cutting tool like a new cuticle clipper or new sprue cutter.  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.

  4. 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 tray.  Try to make the cut so that you do not to have to move the tool or the model when cutting.

  5. Large models like big, hollow turrets, boxy fire control directors and pilot houses will have many internal supports that are difficult to reach.  Cut the supports nearest the tray first.  Start at the outside, working your way around the model.  Work inwards, carefully cutting away the tray.  Then cut the supports from the model.  

  6. Make final cuts near the attachment point.  Try not to twist, pull or push when cutting.

  7. Gently trim or sand away any remaining "nubs" just like you would on models made from injection-molded polystyrene plastic.

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

Cleaning your model.  If you find a spot on your model that feels a bit sticky or you need to clean your 3D-printed model, isopropyl alcohol is recommended.  You can also use mild dishwashing liquid like "Dawn", "Fairy", "Joy", "Simple Green" or baby shampoo (no conditioner) in warm water.  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 to clean your models.  Acetone and acetate can melt 3D-printed plastic.

No wax or oil.  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 release agent is necessary. 

Normally, no ultraviolet (UV) light post-curing is needed.  Your model is created when ultraviolet light chemically hardens liquid resin.  After printing and cleaning, we place your gray resin model in a UV light booth to fully harden the resin before we ship your model to you.  No additional exposure to ultraviolet (UV) light, called "post-curing", should be needed.  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.

Model Assembly Instructions.  No assembly instructions come with your model.  Please study photos and renderings on the product webpage.

Glue.  Cyanoacrylate (CA) "super glue" works best with this material.  For larger parts, epoxy can be used.  Liquid glue intended for injection-molded plastic models such as "Testors Liquid Cement" does not work with gray resin.  Superglue remover containing acetone may harm the plastic.


Paint.  Gray resin plastic accepts 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.  To determine how your paint will behave with 3D-printed gray resin, test your paint on the 3D-printed gray resin tray that your models come attached to,  Remove your models from the tray and paint the smooth tray bottom without primer.  Check your results and proceed accordingly.  Do not use methy ethyl ketone "MEK" as an airbrush paint thinner.  MEK is known to react with 3D-printed plastics and produce a powdery residue that is difficult to remove.

Shapeways 3D-printed products.  Some Model Monkey designs, like metal nameplates and very big models, are not suitable for gray resin printing.  Those models can be ordered from Shapeways.  Products ordered from Shapeways are sold, printed and shipped by Shapeways, not Model Monkey.  Shapeways prints models in various materials but not gray resin.   Click here to see Shapeways' website to learn more about their materials and their cost. 


Shapeways' acrylic plastic is chemically different than Model Monkey gray resin.  Shapeways' acrylic plastic models are printed using a different process than our gray resin models.  Shapeways' 3D-printing process includes wax and oils.  Clean Shapeways' plastic with isopropyl alcohol or mild dishwashing liquid like "Dawn", "Fairy", "Joy", "Simple Green" or baby shampoo (no conditioner) in warm water.  Place your Shapeways models in direct sunlight or under another ultra violet light source for an hour or so to ensure all of the plastic is fully hardened.  If not fully hardened, enamel paint may not cure properly on Shapeways' acrylic plastic.  CA glue works best with Shapeways' acrylic plastic.

CAD files.  The computer aided design files used to create Model Monkey products are not for sale.

Copyright.  All of the models offered in this catalog are protected by US and international copyright laws.  Model Monkey products may not be copied or re-cast.  This catalog and any photographs and computer generated renderings of the products appearing within this catalog are also protected by copyright.  Renderings and photos may not be used without permission.

Material Safety Data Sheet for gray resin (click here).