K'nex Rubber Band Gun




Introduction: K'nex Rubber Band Gun

About: Hi, I'm Yttrium. I've been into engineering and programming for a very long time and aspire to be an electrical engineer or a software developer. I enjoy experimenting with new ideas and try to go where nobo...

Hello Instructables Community! I present to you my new powerful K'nex Rubber Band Gun. Due to its unique firing system, which pivots on an offset rod, it is impossible for 2 bands to slip through and fire. It can hold an infinite amount of rubber bands, although the trigger gets slightly harder to pull with each additional band. Its structure is very stable, and its finishing touches ensure that it is very comfortable and aesthetically pleasing. It is easy to use, with a ratchet that enables loading of bands without pulling back the trigger. Overall, I am pleased with the final product. Here is a list of pros and cons:


  • Easy to Build
  • Comfortable
  • Reliable
  • Powerful
  • Nice Trigger
  • High Capacity
  • Easy to Load
  • Aesthetically Pleasing
  • No Broken Pieces
  • Band Clip (Optional)


  • Uses Rare Pieces
  • Fires on Trigger Release
  • High Stress on 1 Piece

With that said, let's move on to the fun part: The Building!

Also, feel free to leave comments on this Instructable. I'd love to have your feedback.

Step 1: Frame

Here is the basic framework of the gun.


  • #1: Build this piece.
  • #2: Make another one.
  • #3: Add 18 blue rods to one side of the Frame.
  • #4: Another view
  • #5: Another view
  • #6: Another view

Move on to the next step!

Step 2: Structure

Here are the structural pieces of the gun body. All of these pieces floating around will be attached to the gun body in the Assembly step.


  • #1: Make 12 of these.
  • #2: Make 2 of these.
  • #3: Make this piece.
  • #4: Make 2 of these.
  • #5: Gather this

You are now ready to move on to the next step.

Step 3: Grip

The grip is difficult to make. A vise can be a good idea, but I attach as many connectors to the rods as I can until I can't fit any more. Then I bend one rod up slightly, out of the grooves in some of the connectors, and I attach the rest to the straight rod. When I am done, I just force the bent rod into place. I have found this to be the most efficient and least painful method around.


  • #1: Make the Grip.
  • #2: Finish the Grip.
  • #3: Another view

The grip is finished. Move on to the trigger assembly!

Step 4: Firing System

Here is the trigger and firing system. The trigger actually rises to meet the cog, preventing any accidental slips from occurring and letting 2 bands fire simultaneously.


  • #1: Build this compact piece.
  • #2: Another view
  • #3: Another view
  • #4: Build this small cog.

These complex pieces and all the others will be compiled in the next step!

Step 5: Assembly

This is where it all comes together. Grab all of your pieces and the frames, and we can get started!


  • #1: Gather these.
  • #2: Attach the orange structural pieces to the Frame.
  • #3: Another view
  • #4: Another view
  • #5: Another view
  • #6: Add the Grip to the Frame.
  • #7: Attach the first level of structure to the Frame.
  • #8: Another view
  • #9: Add 3 green rods to the Grip.
  • #10: Gather a small rubber band.
  • #11: Loop it around the end of the second structural layer.
  • #12: Attach the second structural layer to the Frame.
  • #13: Another view
  • #14: Another view
  • #15: Attach the final structural layer to the Frame.
  • #16: Insert the white rod and add the 2 final structural pieces to the Frame.
  • #17: Insert the Firing System. The lower white rod of the trigger sits in the hole of a white connector.
  • #18: Another view
  • #19: Attach the 3 gray connectors and the 2 gray spacers.
  • #20: Loop the small rubber band around the white rod of the trigger.
  • #21: Attach the second plate of the Frame.

Finally! This step is complete. Now you can move on to Streamlining!

Step 6: Streamlining

This is where the ugly and uncomfortable ends of rods get covered up, making the gun look much better.


  • #1: Gather these. (32 of the spacers)
  • #2: Slide 1 blue spacer onto all 16 exposed rods on one side of the gun (see picture notes for exclusions).
  • #3: Another view
  • #4: Another view
  • #5: Attach the Streamlining parts over the exposed rods.
  • #6: Another view
  • #7: Another view
  • #8: Add 3 black y-clips to the Grip/Frame.
  • #9: Attach the 2 gray clips to the remaining exposed rods.
  • #10: Repeat steps 2-8 on the reverse side.

This step is done, and I very much hope your gun looks something remotely like a gun now. If it does, proceed to the next step!

Step 7: Band Clip (Optional)

In this step you will create a storage area for ammunition that you want to have neither in your pocket nor on the firing wheel. To do so, follow these 2 simple steps:


  • #1: Gather 6 green connectors.
  • #2: Attach them to 2 blue rods on the gun body.

Your gun is now complete! Let's move on to Loading and Firing.

Step 8: Loading and Firing

To load your gun, put a rubber band in the muzzle and pull it straight back to the gray connectors behind the wheel. Hold it on top of the gray connectors and then release it. It should pop straight into place in the small V between the green rods on the white firing cog. Then simply pull back the cog until it clicks once, and it will lock into place. The gun has very high capacity, but I would load no more than 4 or 5 powerful rubber bands onto it at any one time since the trigger becomes unreasonably hard to pull. To fire, pull back the trigger. Once you have done this, the gun will cock itself. Release the trigger and it will instantly fire. Have fun with this, and modify it. Make two, if you want, so that you can have rubber band wars with friends. I have tried this and found that they work very well for this purpose, although they can sting quite a bit. I am NOT responsible for any damage you or anyone else does to yourself, others, or objects. Be safe with this gun and wear eye protection at all times. With that said, enjoy shooting down targets, people, cats, velociraptors... And things that will shoot you back!



    • Game Life Contest

      Game Life Contest
    • Organic Cooking Challenge

      Organic Cooking Challenge
    • Tiny Home Contest

      Tiny Home Contest

    22 Discussions

    I have built a gun that uses this mech and i was wondering if i could have permissions to use this mech and post my gun if i give you credit for the mech.

    Thanks Sonic Broom

    1 reply

    Sure! That's what Instructables is for... Thanks for asking, though, I like it when people do that.

    Thank you for your feedback. I worked long and hard to make it look good, feel good, and perform well.

    I built it and it works rely nice one thing to consider would be to make the handle not as thick so that it is more comfortable also it would be supper cool if you could make a pistol version of this. Thanks for the great build and clear instructions!

    3 replies

    You're welcome. I'm glad you liked it. I could make the handle thinner (simply by using white rods instead of blues) but I modeled it for a rather large hand, as mine are. Feel free to modify its design a bit, and possibly leave me pictures in a comment!

    I was thinking of using this mech in a diffrent gun of mine would it be okay if i post it if i give you credit for the ratchet mech it is so clever!

    You're welcome. I'm glad you liked it. I could make the handle thinner (simply by using white rods instead of blues) but I modeled it for a rather large hand, as mine are. Feel free to modify its design a bit, and possibly leave me pictures in a comment!

    Thank you. I spent a lot of time making it look clean. Your contest entry looked really nice too.