Introduction: K'nex Whisper Pistol [Semi-auto, Unique Mech, 6 Shots]

This is NOT your average rubber band gun.

K'nex gang! I have for you today a semi-automatic pistol which features a new-ish mech. It is similar to TheDunkis' SYCAMORE gun (Also see this semi-auto by Blue Mullet and Oblivitus' full/semi auto) mech but with rubber bands added. I actually came up with this on my own, but after some searching I found that a mech somewhat similar to mine had already been invented. Yet, it is a lot different in the way it operates so I do consider it to be new-ish. If anyone has any problems with 'unique mech' being in the title, I'll take it out. I don't wish to steal credit from anyone.

It may have a few problems, but keep in mind it is an 'experimental' mech. You will be seeing a few more of these 'experimental' guns from me, as I am working on several others, more or less outlandish than this one :)

My hope for this instructable and any upcoming knex guns is that it sparks some new life in the knex gun community, and spawns the next generation of knex gun makers. Yes I am aware of that sounding very nerdy.

This gun works by a trigger-operated lever which moves a hammer-like apparatus which then unclips one of the grey clips, mounted on a blue rod and pulled over the front of the barrel by rubber bands, and the next one moved up into position by a pusher band.

Here is a GIF of it firing!That hallway is about 25-30 feet long.The shots easily hit the end of the hallway with some force left over.

For all the steps, and for your convenience, the instruction text
will be placed in both the picture notes (Top of the image) and also in the text :) It's not necessary to read them, the pictures should be straightforward. But they are there if you need them. Any image notes that are not in the top-left corner may be of use and could help with tricky steps and I recommend reading those. Any mistakes I made in taking the pictures will also be noted. I'll mark the pictures that contain those with *.

Some nice features:

  • This gun really is incredibly silent, with only the 'click-click' of the grey connector shots unclipping.
  • Literal 'Whoosh' sound as the shots fly through the air.
  • It has a very comfortable grip.
  • Six shot capacity, it is loaded to the brim.
  • Internal mag.
  • True trigger + trigger guard.
  • Easy on the parts count.
  • You can fire as fast as you can pull the trigger.
  • New take on an old mech!
  • Easy and short trigger pull.
  • Gets 30+ feet easily.
  • Dual-weild worthy!

Good and bad, these come down to personal preference.

  • Cut parts, but only two.
  • Each shot is powered by it's own rubber band, so this is essentially a rubber band gun with weights attached to the bands.
  • Rather large for a pistol.
  • A skeletal look, which is a plus for me.
  • Range may be lacking, depends on what you consider to be good range. Keep in mind it has an extremely high rate of fire to compensate.
  • Rather long reload time.


  • May need tweaks? I will post any tweaks I make on the last page.
  • Sometimes, the last shot will take an extra bit of time to get into position. You can fix by stretching the mag band further, but not too much that the first shot fires two at once, or refuses to fire.

Parts list! (309 total parts)

This list is enough to make the full gun and six rounds.

Rods: 88

  • Green: 36
  • White: 19
  • Blue: 25
  • Red: 3
  • Grey: 5

Connectors: 127

  • 1-slot Grey: 19
  • 2-slot Light Grey: 40
  • 2-slot Orange: 9
  • 3-slot Red: 24
  • 4-slot Green: 11
  • 5-slot Yellow: 9
  • 8-slot White: 3
  • 4-slot 3-D Purple: 2
  • 7-slot 3-D Blue: 10

Misc: 92

  • Y-Connector: 19
  • Blue clip: 2
  • Tan clip: 10
  • Blue spacer: 47 (Can be replaced by silver)
  • Silver spacer: 9
  • Female ball joint (Or half of an orange connector): 1
  • Small black wheel: 2
  • Dome: 2

Broken parts: 2

  • Rod end: 1
  • Cut grey (See step 2): 1


  • Size 32 rubber band: 7
  • Size 64 rubber band: 1
  • Scotch tape (Optional)

Step 1: The Barrel

We'll start with the most difficult part, the Barrel.

You will need the following parts for this step:


  • White: 1
  • Blue: 1
  • Red: 3
  • Grey (Or black): 5


  • 1-slot Grey: 6
  • 2-slot Light Grey: 35
  • 3-slot Red: 2
  • 4-slot Green: 2
  • 5-slot Yellow: 3


  • Y-connector: 3
  • Tan conector: 6
  • Female ball joint: 1
  • Blue spacer: 10
  • Silver spacer: 9

If you want, you can replace all the grey rods with black rods to strengthen the barrel further.

You could also replace the female ball joint with half of an orange connector, that may work better. I have not noticed any difference yet however.

  1. Build.*
  2. Add eight grey connectors.*
  3. Add eight more grey connectors.
  4. Insert a red rod and prepare two y-connectors.
  5. Flip the barrel and attach the y-connectors onto the red rod from the other side.
  6. Add two grey rods and prepare the parts shown.*
  7. Add some of the parts to the front of the barrel.
  8. Add the rest to the back.
  9. Add a white rod to the front and prepare these parts.
  10. Add the ball joint and the spacer.
  11. Add the grey connector.
  12. To the back of the barrel, put on a blue rod and find the parts shown.
  13. Attach them to the blue rod.
  14. Attach 1 dark and 9 light grey connectors.*
  15. Attach 10 more light greys.
  16. Build and get.*
  17. Insert into the barrel, and push the front-most light grey connectors up.*
  18. Add the rest of the parts and push the light greys back.*
  19. Insert a grey rod and find parts
  20. Add them onto the rod.
  21. This is the hardest section to build, but you got it! The completed barrel!

Step 2: Trigger and Grip

Now we will be making the Trigger and the Grip.

You will need the following parts for the Trigger and Grip:


  • Green: 7
  • White: 7
  • Blue: 8


  • 1-slot Grey: 1
  • 2-slot Light Grey: 5
  • 2-slot Orange: 5
  • 3-slot Red: 9
  • 4-slot Green: 3
  • 5-slot Yellow: 1
  • 7-slot 3-D Blue: 2
  • 8-slot White: 1


  • Y-connector: 4
  • Blue clip: 1
  • Blue spacer: 3
  • Small black wheel (see pics): 2

Broken parts:

  • Rod end: 1
  • Cut grey 1-slot (see pic 1): 1


  • Scotch tape (Optional)


  1. Cut a grey connector as shown.*
  2. Make this.
  3. Make this.
  4. Make this.
  5. Prepare to assemble parts.
  6. Begin assembling.*
  7. Finish assembling the hammer.*
  8. Make the trigger.
  9. Now we will begin working on the grip. Make both of these.
  10. Add three white rods and a light grey connector to one of the things.
  11. Make this.
  12. Also make this.
  13. Join them and add one green connector.
  14. Connect it to two of the white rods on the first layer.*
  15. Add on the last layer.
  16. Add a wheel to both sides. The grip is now complete!

Step 3: The Main Body

So close to shooting it! Just one more section to build.

You will need the following parts for this step:


  • Green: 29
  • White: 11
  • Blue: 16


  • 1-slot Grey: 6
  • 2-slot Orange: 4
  • 3-slot Red: 13
  • 4-slot Green: 6
  • 4-slot 3-D Purple: 2
  • 5-slot Yellow: 5
  • 7-slot 3-D Blue: 8
  • 8-slot White: 2


  • Y-connector: 12
  • Tan clip: 4
  • Blue clip: 1
  • Blue spacer: 34 (Can replace with silver spacers)
  • Dome (See last pic): 2


  1. Outer layers. Make two of these.
  2. Add 10 blue rods and prepare parts.
  3. Add the parts.
  4. Install the trigger mechanism.
  5. Another view
  6. Make one
  7. Attach it here.
  8. Make this.
  9. Put it here.
  10. And then make this,
  11. And slide it on.*
  12. Prepare parts
  13. Add them on.*
  14. Finally, put the last layer on.*
  15. Add a dome on both sides. The main body is now complete!

Step 4: Assembly and Band Placement

Now the parts of the gun have been constructed. All that needs to be done is assemble them and add the rubber bands!

You will need the following parts for this step:

  • Grip
  • Barrel
  • Main body


  • Size 32 rubber band: 1
  • Size 64 rubber band: 1


  1. Snap on the grip.
  2. Connect the white rods.
  3. Open up the layers to make room to put on the barrel.

  4. Preparing to attach the barrel.*
  5. Attach the barrel.
  6. Connect the green connectors.
  7. Put on the trigger band.*
  8. (and 9) Put on the magazine band.

Step 5: Ammunition, Loading, and Firing.

Now the gun is done! Make the ammo and fire away!

You will need the following parts for this step:


  • 1-slot Grey: 6


  • Size 32 rubber band: 6


  1. The round. Loop a rubber band onto a grey connector to make.
  2. Make six.
  3. Where to load them.*
  4. Push it onto the red connector, over the rubber band.
  5. Slide it down and snap it onto the blue rod.
  6. Stretch the band to the front hook of the barrel.
  7. Move the magazine band over the blue spacers. They act as wheels and keep the mag tension even.
  8. Load the rest of the rounds by pushing the rounds down, snapping it onto the blue rod, and stretching the band onto the hook.

  9. The loaded magazine.
  10. Finished! Pull the trigger to fire. Thanks for building!

Step 6: Extra

If anyone makes one and wishes for me to post their image of it here, or if I make any tweaks, changes, or upgrades to the gun, you will find those here.

Thank you for checking out my instructable!