Commercial balloon pumps can be very expensive. Some require batteries and others are difficult to operate. The basic premise behind a floor pump is to create a simple "plunger" effect that forces air through a nozzle to inflate the balloon. Plans range from very simple to more complex, but they all work the same. The balloon pump will take around one day to complete including the drying times.
Apply the PVC glue to one end of the length of 3-inch PVC pipe and to the inside of the 3-inch PVC base.
Press the two pieces together firmly and set aside to dry.
Drill a hole in the centre of the 4-inch PVC cap. The size depends on the nozzles chosen.
Add threads to the hole using the tap. The size depends on the nozzles chosen.
Wrap some Teflon tape around the base of one of the nozzles and screw it into the tapped hole. The Teflon tape helps prevent air from escaping from around the base of the nozzle.
Sand down the interior of the 4 to 3-inch coupler until the 3-inch PVC pipe can pass all the way through with minimal friction. This is done using the Dremmel tool or sandpaper to remove the interior ridge of the coupler.
Fit the 3-inch rubber cap onto the 3-inch PVC pipe.
Verify that the coupler continues to slide freely over the rubber cap and the PVC pipe. Continue to sand the coupler until both the cap and the pipe pass through with minimal friction.
Glue the 4-inch PVC pipe to the 4-inch PVC cap with the attach nozzle and set them aside to dry.
Wait for the pieces to dry for at least 12 hours.
Attach the 4 to 3-inch coupler to the 4-inch PVC pipe and nozzle assembly. Do not use glue.
Apply vaseline or similar lubricant to the inside of the coupler and the outside of the 3-inch PVC pipe.
Slide the 4-inch PVC assembly over the 3-inch PVC assembly.
Hold a balloon over the nozzle, lift up on the 4-inch assembly while standing on the base, then push down to inflate the balloon.