Introduction: The C3.3 Lethal Armor-Piercing Lego Crossbow

Picture of The C3.3 Lethal Armor-Piercing Lego Crossbow
This is the third (and last) mod of the C3 Crossbow, and is by far the most powerful I've ever made. This crossbow shoots sharpened knex bolts, or pencils, at high speeds. The crossbow can fire 60+ feet, and has 9 rubberbands tied together in 3 sets of 3. This crossbow is very powerful, and could kill someone if fired at close range (I'm not exaggerating).


-Very Powerful (60+ feet)
-Very Strong (Can Penetrate Cardboard, CDs, Cans, Ballistics Gel)
-Fairly Accurate
-Fires Pencils or Knex rods
-Good Sight
-No Recoil
-2 Handholds


-Fairly long reload (4 seconds)
-Fairly heavy (2 pounds)



Step 1: Bottom Part 1

Picture of Bottom Part 1

The bottom part of the handle.

Step 2: Trigger

Picture of Trigger

easy to make

Step 3: Bottom Part 2

Picture of Bottom Part 2

This part works on the area that holds the counterweight rubberbands.

Step 4: Bottom Part 3

Picture of Bottom Part 3

This completes the bottom part for now.

Step 5: Forward Handle

Picture of Forward Handle

VERY easy. self explanitory

Step 6: Rubber Band Holders Part 1

Picture of Rubber Band Holders Part 1

This step makes part of the front of the crossbow which holds the firing rubber bands.

Step 7: Rb Holders Part 2

Picture of Rb Holders Part 2

The other half of the holders.

Step 8: Runway Part 1

Picture of Runway Part 1

This step creates the base of the runway.

Step 9: Runway Part 2

Picture of Runway Part 2

Building up the runway.

Step 10: Runway Part 3

Picture of Runway Part 3

Finishing the firing runway. Ive seperated the sets of pieces with one stud on top into groupings to make it easy to tell which ones are which in the closeups.

Step 11: Back Section

Picture of Back Section

In this step, the back of the gun is built up.

Step 12: Firing Gear

Picture of Firing Gear

This is the gear which the rbs are put on to fire. This step also builds up the area around the firing gear.

Step 13: Rear Sight

Picture of Rear Sight

This step makes the sight placed on the back of the crossbow.

Step 14: Firing and Counter-weight Rbs + Attaching the Handhold

Picture of Firing and Counter-weight Rbs + Attaching the Handhold

You need 9 Total Large Firing Rubberbands, and 4 Smaller, thicker counter-weight rubberbands.

Step 15: Ammo + Loading

Picture of Ammo + Loading

For ammo, you can use either pencils, or the sharpened knex pieces shown. To sharpen the knex pieces, just take the red rod shown and sharpen it in a regular pencil sharpener until it is as sharp as possible. Then, attach the orange connector to the back, and that is your ammo. Oh, and if you kill or injure someone with this gun, I take no responsibility for your actions.


FaarisI (author)2016-02-06

hey i really want to make this but i dont know the parts. can you make a brick list?

FaarisI (author)2016-02-06

hey i really want to make this but i dont know the parts. can you make a brick list?

jlandreth1 (author)2014-07-19

Hi. Your crossbow gave me ideas for my already made lego crossbow (check it out on my profile). I never thought about using more than one rubber band. If I did with mine, it would be crazy because mine already shoots 40+ feet with one rubber band... I may now be about to make something very dangerous!

speedracer425 (author)2012-08-26

i subscribed to you and you deserved it

Tawhid K (author)2012-07-31

which one of your crossbow is the strongest one

Tawhid K (author)2012-07-31

which of your cross bow is the most powerful one

Dr. Brickinstein (author)2012-07-04

I built it its AWESOME!! I got it shooting nails!!!

vlerky (author)2010-10-21

Hey i build this! (with a few mods) Ultra nice thing!! high firepower!(poor box)
explanation of pictures:
1 the whole thing
2 runway
3 the custom handle
4 the custom handle(again)
5 magazine for 3 arrow's
6 the poor box

kingofthespazs (author)vlerky2012-03-15

can you make a how to page

vlerky (author)kingofthespazs2012-03-16

I'm sorry, I don't have it anymore, but follow the instructions above from bitterberry9, the modifications shouldn't be hard to reconstruct.


tooter365 (author)2009-08-06

lesson learned: dont shoot little sister with this with 6 rubber bands and a toothpick attatched to a wood shaft. very skin piercing.

Bitterberry9 (author)tooter3652009-08-07

ouch :(

That sucks

meaner6788 (author)2011-12-26

you should make a clip

meaner6788 (author)2011-12-26

dude awesome except i dont have all the pieces :)

speedracer425 (author)2011-07-28

I just built the C3.2 today and I wonder if I could change runway so I could make this weapon of choice.- -
u. And how do I get the ballistics jell like Mythbusters?

yeldarbtgs (author)2011-06-28

I shot a worm It died ;(

yeldarbtgs (author)2011-06-28

You said to have a 6x9, but it is 6x8 on the picture

pizzabakker1 (author)2009-08-25

how could you !!?? use knex and lego together !!!... :(... knexers hate lego builders.. :´( not good dude !

ya i know lol but think of it as a first step to a peaceful relationship maybe?

lizard657 (author)Bitterberry92011-06-12

Wait.... you call a possibly lethal crossbow a PEACEFUL relationship?!?

thats beatifull !!.. no thanks, I like to keep it at knex.. anyway, nice crossbow dude, realy nice..

Lhtrf (author)2011-03-25

time to build one and store it somewhere accessible for the case of a zombie attack!

Raven Destroyer (author)2010-08-08

eh if it can shoot pensils why you then use knex and so it can then also fire homemade rounds found in the woods after 5 arrows or so you mastered that and then you have free rounds and don't have to use knex but this is freaking cool it starts my urge to find my lego XD realy good done

Well, for pencils and pens, you have to add some paper padding or stuff on the back end to make the ammo wider. #64 rubber bands tend to fly over regular pencils. Also, K'Nex pieces seem lighter.

cxt1 (author)2010-08-12

You know the C3.3 crossbow would be way better if you incorporated the C4's quick relode part on the C3.3 just imagine launching 5 lethal arrows/bolts so quickly!

Bitterberry9 (author)cxt12010-08-12

ya I considered that, and it would be cool, but in order to give each bolt power, you would need to have 3 sets of rubberband strings/bolt, so in total 15 strings of rubberbands, which would unfortunately would be WAYYYYY too much stress for the gun/firing gear to handle. it would be cool tho :)

sacram98 (author)2010-07-24

lol i feel sorry for the cd but the gun is really cool

totoandamigo (author)2010-05-25

best f ing crossbow yet!!!!!!

superjedy (author)2010-03-15

Awesome crossbow spmetimes it took some times to find the parts but its done and ready to shoot.

SonicX 22 (author)2010-02-16

 LOL! i noticed that you r using Imovie (YAY A MAC PERSON)

i have a mac too

brooklynlord (author)2010-01-20

Do you have any idea where i can get the angled lego pieces for the pivot part of the trigger? i have a piece similar to that, but one end is long  and i only have 1.

Bitterberry9 (author)2009-12-12

 I'm trying to figure out why this gun has such a low rating....if people are wondering if the videos a fake, its definitely not, it really is that powerful, and if you don't believe me, build it yourself

Fred the Penguin (author)2009-09-19

knex pwns lego 20/10

legomman200 (author)2009-08-11

I just built it like six hours ago. I love it

tooter365 (author)2009-08-06

its like a red dot site on a kar98k on cod!

n1k3sh0x (author)2009-07-26

this is a really cool cross bow leatheal wepon i built it !@!@!!!@!@!...l

StyleCore (author)2009-07-22

That looks really cool, but legos are too complicated for me.

DJ Radio (author)2009-07-20

what the hell is this doing in the knex section.... oh wait. It fires knex rods.

About This Instructable




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