The C3.3 Lethal Armor-Piercing Lego Crossbow

Introduction: 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

The bottom part of the handle.

Step 2: Trigger

easy to make

Step 3: Bottom Part 2

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

Step 4: Bottom Part 3

This completes the bottom part for now.

Step 5: Forward Handle

VERY easy. self explanitory

Step 6: 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

The other half of the holders.

Step 8: Runway Part 1

This step creates the base of the runway.

Step 9: Runway Part 2

Building up the runway.

Step 10: 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

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

Step 12: 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

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

Step 14: 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

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.



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    40 Discussions

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

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

    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!

    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

    3 replies

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

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

    2 replies

    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?

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

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