Here is a collection of optional additions to the MBAR-2. This includes:
-Vertical grip (Also works for MAR, MAR-2, and MBAR)
-Bayonet (Also can work on the MSAU)
-Bi-pod
-Grenade launcher (Pull trigger and lever trigger)

MBAR-2 Instructable

More Instructables by me.

The images show the additions on the MBAR-2.
Image 1: Bayonet and vertical grip
Images 2-3: Bi-pod
Images 4-5: Grenade launcher

Step 1: Front Grip

Much explanation should not be neccessary. Make as shown in the first image and then attach as shown in the second image to the gun.

Step 2: Bayonet

Image 1: Make 2 of these.
Image 2: Make 1 of this.
Image 3: Add white rods where indicated.
Image 4: Place the part so the white rods go through the connectors as shown.
Image 5: Cover with the last part as shown.
Image 6: Connect to the rail near the end of the barrel as shown.

Step 3: Bi-pod

Follow the images:

Image 1: Make 2 of these.
Image 2: And 2 of these as well.
Image 3: Connect them together so you get these.
Image 4: Now add white rods to a white connector as shown.
Image 5: Add green connectors and make a part so it looks like in the image.
Image 6: Cover with a white connector.
Image 7: Attach blue rods to the green connectors as shown.
Image 8: Add red connectors here.
Image 9: And on the reverse side.
Image 10: Attach the hinge part ot the legs as shown.
Image 11: Attach bi-pod to the gun as shown.
Image 12: When not in use and folded the Y-clips on the legs are attached to the rail as shown here.
Image 13: Bi-pod being used.

Step 4: Grenade Launcher: Launcher

Follow the images:

Image 1: Make these. The rods are blue.
Image 2: Build onto that so it looks like so. Notice the white rods.
Image 3: Add blue spacers and red rods with gray connectors on both sides.
Image 4: Build on so it looks like so. Nearly the same as before but with 3D connectors.
Image 5: Add green rod and white rod with tan clip.
Image 6: Add orange connector.

For a Pull Trigger:
Images 7-8: Make this part.

For a Lever Trigger:
Image 9: Make this. Notice all the white rods.
Image 10: Add on hinge, red/gray connector, and blue spacers as shown.
Image 11: Build onto that to get this.

Assembling the Components:
Image 12: Pull trigger attached.
Image 13: Lever trigger attached.
Image 14: Grenade launcher attached to gun's rails.

Step 5: Grenade Launcher: Grenade

Follow the images:

Image 1: Make this. Notice how the rubberband is placed and that the orange connector is twisted.
Image 2: Add gray spacers (can be blue as well) and place a gray connector at the end as shown.

Step 6: Grenade Launcher: Use

To load follow the images:

Image 1: Hook the rubber band on the tips of the grenade launcher.
Images 2-5: Hook the rubber band on the ammo's yellow connector as shown, pull back and insert in between the white connectors and push the white rod up to lock it in place.

To Fire:
Pull the trigger if pull trigger. If lever trigger, push upwards in the dirrection of the barrel.

Step 7: Warning!!!

Warning- These K'nex may cause harm or injury if misused. Do not point it at people. I am not responsible for damage, injury, or death caused by this instructable. Do not treat this just as a toy but as a real, dangerous weapon.