Plans for building these "locomotive whistles" are available from

  Doyle Lane Restorations
  PO Box 1201
  Middletown Springs, VT 05757-1201 USA
  fax:  802-235-2375
  tel.: 802-235-2900
  email: <pianoman@vermontel.net>

I built one and used it for a doorbell for years and now it resides
on top of the toy counter of the Tokyo Mitsukoshi Wurlitzer.  It
sounds in the key of D-flat and is very useful when I play "I bin
wukking on de railroad!"

Vic Searle, Curator, Mitsukoshi Wurlitzer
Tokyo