Vacuum Bullet for DN50 pipe - hollow shell

You've seen the ping pong ball on Mythbusters go faster than the speed of sound and punch a hole in a ping pong bat! ... yea. thought we'd try that one at home.

The DN40 pipe that I got here in New Zealand was too small for the 40mm ping pong ball. So I ended up using DN50 and of course that was too big for the ping pong ball.

SOLUTION... print your own... only not a ball. A hollow shell. The design could be improved upon, its set for 0.3mm thickness wall and depending on your printer a 0