Looking for speakers in 28mm

[6milPhil]

  Got a top secret project in the works for Salute 2011, lots of hacking etc, but one thing I'd rather buy than make is an old style tannoy public address speaker, or four.*  

They look a bit like these.





Can anyone suggest a source?

Thanks in advance!  

*That's models, non-working, etc... 

[Tobsen77]

Golf tees?

[Hammers]

Clever man, that Tobsen chap.

[6milPhil]

Good suggestion thanks!

I've settled on a spare piece for a Dinky toy via ebay as suggested by a chum at GWP.