ANVIL - Shell Ejecting Nerf Shotgun (Box Magazine!) (3D Printed Nerf Blaster)

The ANVIL is a 3d printed Nerf box-magazine shotgun blaster that fires and ejects Silly Shells! It's spring powered, with a pump action prime, and quickly reloadable magazines. Yes, it actually fires multiple darts at once!

READ THE "Print Info" SECTION of this description page before printing the blaster!

Changelog is at the bottom of the description text.

Blaster Overview and Firing Demo: 

Please refer to the file listing for Silly Shells and the ANVIL magazines to download them all and get more information.

Please check the shell compatibility spreadsheet to see which Silly Shells work in this blaster.

READ THE "Print Info" SECTION of this description page before printing the blaster!

There is a full written and illustrated assembly guide for the ANVIL, available as a PDF download in this Printables file repository :) 

 THE ASSEMBLY GUIDE IS STILL W.I.P... I was sick and had 2 exams the week leading up to release, on top of midterms. Sooooo now I'm getting around to working on it. If you have printed parts and the guide is not out yet, you should look at the assembly guide for the Battle Axe and the Breacher, both of which have aspects very similar to this blaster. Here is the rough draft of that assembly guide for now: https://docs.google.com/presentation/d/1DeSEaa5kB8AoEqVfGzngqIB_OcZ4hYImX-IAxN92P7o/edit?usp=sharing

Picatinny mounted Silly Shell carrier/holder files here: https://www.printables.com/model/1016480 

 Get the magazine files here: 

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“What is the ANVIL?”

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The ANVIL is a 3d printed DIY Nerf-style foam dart blaster, which uses a 3d printable shell (Silly Shells) and magazine (ANVIL mags) to hold several darts at once, and fire multiple darts each time you pull the trigger.

The ANVIL is able to fire many different types of foam projectile, including Nerf Elite darts, Nerf N1 darts, half darts, Rival balls, Mega, MegaXL, and more!

That all adds up to make the ANVIL a very fun, and very satisfying shotgun-style blaster! Especially with quick reloads, you can unleash a wall of foam at your command. 

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Sellers

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A full list of non-US sellers can be found here: https://www.stuffbysilly.com/wheretobuy

Hardware kits are available from these sellers:

• OutOfDarts: https://outofdarts.com/products/sillybutts-anvil-hardware-kit-shell-ejecting-aa12-shotgun-blaster

• SilverFoxIndustries: https://silverfoxindustries.shop/collections/designs-by-sillybutts

• BearsWares: https://bearswares.shop/products/a-n-v-i-l-by-sillybutts

Fully printed blasters are available from these sellers:

• OutOfDarts: 

  • Printed parts and fully assembled blasters: WIP

• SilverFoxIndustries:

  • Printed parts and fully assembled blasters: https://silverfoxindustries.shop/collections/designs-by-sillybutts

Magazine hardware is also available separately if you want to make more mags:

• OutOfDarts: https://outofdarts.com/products/sillybutts-anvil-silly-shell-magazine-hardware-kit

• SilverFoxIndustries: https://silverfoxindustries.shop/collections/designs-by-sillybutts

• BearsWares: WIP

Additionally, Canadians can get kits here without getting thrashed too much by tariffs:

WIP by 1000screws: https://1000screws.square.site/product/anvil-hardware-kit-canada-version-/WSL7UPRTV2TJH74FYMXURC7O

And AKblasterMOD has an international version of the hardware kit + prints: https://www.ak-blastermod.com/product-page/anvil-foam-darts-blaster-toy-by-sillybutt-3d-parts-and-hardware-kit

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“What are Silly Shells?”

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Silly Shells are an ecosystem of 3D printed shotgun shells for homemade Nerf-style blasters! There are many, many different shells to use in each blaster, allowing one blaster to fire a wide variety of ammo types without reconfiguration or modding.

For example, you can fire 3 Elite darts out of one shell, eject it, and then load a MegaXL shell to fire a huge dart at your enemies! Then you can follow that up with a “buckshot” round of Rival balls. Then you can load a Bottlenose shell to hit a person across the field from you.

Silly Shells allow you to use multiple different types of foam ammo in one blaster, and they allow you to fire multiple darts with just one shot of the blaster!

 And ANVIL magazines are a universal standard for Silly Shell magazines. That means that this magazine is used by several different blasters all at once!

Please refer to the file listing for Silly Shells and the ANVIL magazines to download them all and get more information.

Please check the shell compatibility spreadsheet to see which Silly Shells work in this blaster.

 Get the magazine files here: 

Note: ANVIL's magazine and feed system does not fit any shells that have ammo sticking out past the tip (full length Mega or MegaXL), however, you CAN still breech load them one at a time into the blaster for single shots. To use full length MegaXL, use the official "full length MegaXL" remix by VestedClover: 

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Performance

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ANVIL should have the same FPS performance as Battle Axe and Breacher: https://docs.google.com/spreadsheets/d/1Pixa7pvZfWJ54Cy2VnBE_0UdA56MWYw5ja8P_bJ5XCY/

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Print Info

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NOTE: If your hardware kit is using a k25 5.5" long spring, you will need the optional spacer print for the PTguide to prevent the spring from rattling (if spring rattle annoys you)!

Filament usage and print time estimates (PLA filament) (Includes supports and brims for recommended parts):

• All parts together: 1700 grams of filament

• Green: 995 grams (be careful with the green folder prints, or make sure to have 2 spools of the filament on hand in case one runs out!)

• Orange: 315 grams

• Black: 391 grams

• NOTE: THIS ESTIMATE DOES NOT INCLUDE FILAMENT USED FOR PRINTING MAGAZINES!

All STLs are exported in their correct print orientations. 

There is a .3MF file for Bambu Studio, with all the parts in each folder laid out on plates, in their correct orientation, and with correct infill/wall/support settings.

For brims, make sure you set them to “Outer brim only”, so they only form on the outer edge of the parts. If you have it set to both sides, it will cover up screw holes with brims, which makes it harder to assemble.

For supports, make sure you set supports to generate on the build plate only. This will make it a lot easier to clean up your prints.

180mm x 180mm minimum printer size/build plate size.

The “default” print settings for ANVIL are 20% infill, 5 walls (I use Gyroid infill pattern). 
Parts with different settings will have those settings marked in bold text. 

Black

• 20% infill, 5 walls: TriggerGuard, GripBody, SearHolderCap, AlignmentBlocks(two of them).

• 20% infill, 5 walls, BRIM: PicatinnyRail_A, PicatinnyRail_B, PicatinnyRail_C.

• 20% infill, 8 walls, SUPPORTS: Magwell.

• 10% infill, 5 walls: Buttplate, PumpRail.

• 100% (full) infill, 5 walls: ShellStabilizer.

• 100% (full) infill, 8 walls, BRIM: PlungerRod.

Green

• 20% infill, 5 walls: CatchHolder, Nameplates(two of them), RearBrackets(two of them).

• 20% infill, 5 walls, SUPPORTS: EjectionPort.

• 20% infill, 5 walls, BRIMS: BarrelFront, BarrelMiddle, BarrelBack.

• 15% infill, 3 walls: BackPTcover.

• 10% infill, 5 walls: StockFront.

• 15% infill, 5 walls, SUPPORTS: FrontPTcover.

• 20% infill, 8 walls: GripPanel_Right, GripPanel_Left.

• 20% infill, 8 walls, BRIM: StrikePlate, UnionPiece.

• 20% infill, 6 walls, SUPPORTS: Chamber.

• 20% infill, 8 walls, SUPPORTS: Boltface.

• Optional: You can also enable ironing on the CatchHolder. Top surfaces ironing.

• Note: It is helpful to use painted supports on the Chamber print, to make sure the areas around the priming bar holes and the small step near the top of the magazine area are both fully supported.

Orange

• 20% infill, 5 walls: Trigger, Muzzle.

• 15% infill, 8 walls: PlungerGuide_Base.

• 15% infill, 8 walls, SUPPORTS, BRIM: PrimingBlock.

• 20% infill, 8 walls: Ejector, PlungerHeadB, Extractor, SearArm, Catch, MagRelease_Right, MagRelease_Left.

• 100% (full) infill, 8 walls: PlungerHeadA, PlungerCap.

• Optional: You can also enable ironing on the Catch, to make it extra smooth. Top surfaces ironing. 

• Note: Some of the smaller orange parts might benefit from printing with a brim.

For magazine print settings, please go to the Printables page for the magazines: 

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Hardware

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Full hardware list (parts list, bill of materials, whatever you want to call it):

https://docs.google.com/spreadsheets/d/1dDoKI1ABSVgDLMfMWbQWfZAwmBq2UjBUieA1y5g4qwI

Make sure you have the correct tab of the Google Sheet selected. 

Hardware kits are available from these sellers:

• OutOfDarts: https://outofdarts.com/products/sillybutts-anvil-hardware-kit-shell-ejecting-aa12-shotgun-blaster

• SilverFoxIndustries: https://silverfoxindustries.shop/collections/designs-by-sillybutts

• BearsWares: https://bearswares.shop/products/a-n-v-i-l-by-sillybutts

A few notes regarding spring choice:

• I recommend using k25 in the ANVIL, its what I really designed the blaster around.

• Anything weaker than a 788 spring won't do very well with the larger capacity shells (3x elite, 3x rival, MXL, etc). 

• Springs with strength between k25 and 788 are fine, if you want to use the blaster indoors with younger players for example.

• Any springs stronger than k25 don't really increase the performance of the ANVIL. Stronger springs just make the prime harder, and add more wear and tear to the blaster, without making it fire much harder. K25 is the sweet spot of spring strength. 

NOTE: If your hardware kit is using a k25 5.5" long spring, you will need the optional spacer print for the PTguide to prevent the spring from rattling (if spring rattle annoys you)!

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Assembly

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There is a full written and illustrated assembly guide for the ANVIL, available as a PDF download in this Printables file repository :) 

Its really good, go download it. 

There's really good text and picture instructions for every aspect of assembling the ANVIL!

  THE ASSEMBLY GUIDE IS STILL W.I.P... I was sick and had 2 exams the week leading up to release, on top of midterms. Sooooo now I'm getting around to working on it. If you have printed parts and the guide is not out yet, you should look at the assembly guide for the Battle Axe and the Breacher, both of which have aspects very similar to this blaster. Here is the rough draft of that assembly guide for now: https://docs.google.com/presentation/d/1DeSEaa5kB8AoEqVfGzngqIB_OcZ4hYImX-IAxN92P7o/edit?usp=sharing

Notes:

• Make sure ALL the supports are removed from any parts with supports.

• Remember to remove the built in supports from the picatinny rail dovetails.

• Put the rubber plunger padding on the plunger face after assembling the plunger rod and two plunger head parts.

• Lightly lube the Catch front face.

• DONT FORGET the o-rings when you assemble the boltface / plunger cap stuff together!!

  • - 1 big o-ring on the plunger cap before you glue it to the plunger tube.

  • - 1 o-ring between the PTcap and the boltface.

  • - 1 o-ring glued to the front of the boltface.

• I recommend wearing gloves while gluing the plunger tube to the PTcap, and while gluing the -016 o-ring to the Boltface. 

• Round the edges of the plunger tube on the back end so it slides smoothly inside the blaster. Chamfer the inside edge and the outside edge.

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Misc.

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If you print any of my designs, I'd love to see yours! Please consider leaving a Make on the Printables page, and leaving a review!

Thanks to Senrath, Frutiger, and Grey_The_Color for photos! (that's all so far, I'll add more when it's not 3AM on the day of release lol.

Thank you to all of the people who helped to beta test the ANVIL! I could not have done this without you, I appreciate it a ton.

Thank you to everyone who left helpful comments and suggested features and fixes for ANVIL during it's development (almost three years long)! 

The font for the ANVIL logo is Falcon Punch Straight.

The font for the magazine numbers is Teko.

China: 你好！ 我擁有這個設計。 想生產請聯繫我. 你好！ 我拥有这个设计。 如果你想生产，请联系我.

Disclaimer: This is not a toy. This blaster is meant for hobbyists, not children. Blaster must be operated correctly to avoid injury. I am not responsible for any injuries from this blaster. Please use a bright/blaze orange muzzle and barrel cap on this blaster. Consult local laws before building this high powered blaster.

Changelog:

• 10-31-2026: Release

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Donations & Merch

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If you like what I do, please consider supporting me! 

I don't charge for my files, so any donations or merch purchases would be greatly appreciated!

• Patreon (Monthly donations)

• Buy Me A Coffee (One-time donations)

• Fourthwall (NEW!) My merch shop! Go get some cool stickers and fun shirts!

• RedBubble My old merch shop. It's still there, but Fourthwall makes better stuff IMO.