I have seen all sorts of k'nex grenades. and i think at least one launcher but they aren't really universal.
What makes my launcher unique is that it fires almost any knex grenade.
Step 1: The Base
To build the base you will need:
-5 blue rods
-1 blue+grey double clip.
-2 yellow rods
-1 grey rod
-1 black end clip
-2 grey clips
assemble it by looking at the picture bellow. It's very simple.
Step 2: The Ram
This step shows how to build the ram.
you will need:
-1 white connector
-3 white rods
-one (or 2) elastics NOTE: if using a spring don't put elastics on!
-2 grey connectors
Follow the pictures to put it together.
Step 3: Put Together
You will need:
follow the pictures
Step 4: Testing Phase.
Now for the fun part... testing!
just thread on a grenade with a central hole through it or you can just launch the ram.
The pictures just show some ammo on it.