Parts: (Per Grenade)
(1) 1-1/4" PVC Coupling
(2) 1-14" PVC Plug (not end cap)
(1) 3/4" PVC Plug (not end cap)
(1) 3/4" PVC Coupling
PVC Glue

Parts: (Per Shot)
Baking soda
Vinegar
-OR-
Baking Soda
Citric Acid Powder
Water

Step 1: Asembly

Dry fit and glue these conections

The 1-1/4" coupling and ONE of the 1-1/4 plugs (do not push this in all the way, just half way)
The 3/4" coupling and the 3/4" plug

Step 2: Loading and Firing

fill the 3/4" plug/coupling assembly with a spoon of baking soda
fill the 1-1/4" plug/coupling assembly with a little vinegar
put the small tube inside the big tube and push the cap on with all your might (do not hammer)

If you are using citric acid powder add 1/4 of a spoon of that to the small tube
and put in water instead of vinegar

Step 3: More

-It would be far more dangerous but you could use flash powder (fire crackers) or gun powder as the propelant.
-It would be even more dangerous if you glued the top cap in place
-I have an a cannon that I shoot these from(www.instructables.com/id/Relatively-safe-pressure-cannon/)