This is a K'nex bomb I made. The casing is optional but highly recommended. The third picture is the remains of the bomb with the casing. You will have to use three or more #64 rubber bands to get that result. So with that, let's start building. I hope you enjoy it!
Step 1: The Parts List
8 green or black rods
2 white or gray rods
16 long gray rods (optional, only if you want the casing)
2 blue 3D connectors
4 granite or red 3 slot connectors
4 large wheels (only 2 if you don't want the casing)
2 large tires (only if you want the casing)
3 #64 rubber bands
Step 2: The Explosive
Pic 1. What you will be making.
Pic 2. Make these parts. Notice that the slot in the blue connector has to be on the opposite side from the granite pieces.
Pic 3. Add 2 of the four large wheels to the parts you made from the last picture (They just slide into the grooves. They are not attached).
Pic 4. Add the rubber bands. This might take some practice. Put them on one at a time. It might also help to have a friend hold down the middle.
Step 3: The Optional Casing
The casing makes it look better and perform better, but increases size.
Pic 1. Put the last two wheels in the tires.
Pic 2. Put all sixteen gray rods into the treads of the tires.
Step 4: Putting the Explosive into the Optional Casing
Pic 1. Remove two or three of the gray rods from the tires.
Pic 2. Put the explosive into the casing carefully. The side should fit in between two gray rods.
Pic 3. Replace the gray rods. It should look like this.
NOTE: Fill the extra space of the casing with white snowflake connectors for mega-destruction!