By Edwin Wise
The Ping Ponger uses almost half of a rubber racquetball as a disc spring that’s bistable (it can be at
rest in 2 possible states) to propel a ping-pong ball
from a compact PVC launcher.
YOU WILL NEED
1. Make the PVC parts.
Cut all PVC pipe pieces to length. For the body,
cut the ends off the snap tee so it’s 2½" long, then
press-fit the female adapter into the bottom of the
tee and cut it off flush.
Glue the backstop rings together so that one edge
Bevel the inside edges of the barrel pieces with
a file, so they curve to match the shape of the racquetball. Glue the 2 barrel pieces together.
For the handle, sand the 1" repair coupling so it fits
into the 1½" pipe and glue it in place, then glue the
tip of the 1" pipe into this coupling.
PVC glue, epoxy, and
PVC pipe and fittings:
For the backstop:
2" pipe, 1" length
3"-wide ring from the
For the barrel:
2" pipe, 1¾" length
2" insert coupling
part #153807 (as
used in the Boom
Stick, MAKE Volume
13). Cut it down to 2"
long. Also cut a
ring from the scrap.
2. Make a disc spring.
Seat a racquetball into the beveled end of the barrel.
Trace a line around the ball (parallel to the seam)
and cut on this line, leaving a dome. This is your
3. Put it all together.
Glue the backstop into the body (the snap tee),
flush with the back end.
Set the rubber spring on the backstop inside the
body. Slip the barrel in place over the spring, leaving
just enough room for it to spring forward and back.
Don’t glue the barrel; you can remove it to change
Slip (don’t glue) the handle into the bottom of
the body. The handle also acts as a ping-pong ball
holder and ramrod.
Now Ping-Pong Away!
Put a strong, name-brand ping-pong ball into the
barrel, and push it into the spring using the handle,
until the spring sticks open (back), gripping the ball.
Through the backstop, poke the tensed back of
the spring to make it un-spring. Pong!
Edwin Wise is a software engineer and rogue technologist
with more than 25 years of professional experience, developing software during the day and exploring the edges of mad
science at night.
Photograph by Ed Troxell
44 Make: Volume