Step 4: Barrel
How are you going to fire the damned thing if it doesn’t have a firing mechanism.
(Think about it)
Cut two rings out of the acrylic to create supports for the smaller PVC tube with in the larger.
Trace the cut out shape on to the larger tube and cut it out.
Place the smaller tube inside using the ring supports, making sure there is enough of the smaller tube out front of the larger to create the barrel of the gun.
Trace the same shape on to the smaller one and cut it out, matching up the cut outs and glue it all together.
Add a PVC coupler to the rear for the handle to fill the gap between the two tubes and sand it smooth. Then carve in the vent shape at the top front of the entire opening.