Electric Staffs could be made in the railway workshops (as in NSW), or bought from private companies such as say McKenzie and Holland.
The Electric Train Staff (ETS) instrument was patented in 1888 by F.W. Webb and A.M. Thompson of the LNWR. The instruments were initially made in-house at Crewe. In 1893, manufacturing was licensed to the Railway Signal Company of Fazakerley, Liverpool.
Edward Tyer claimed that Webb and Thompson infringed his Electric Train Tablet (ETT) instrument patent of 1878 and was paid £2 per Electric Train Staff instrument produced from 1889-93. The Webb and Thompson patent expired in 1903, following which the design was widely copied, including by the NSWR Signal Branch.
The Tyers Electric Train Tablet system was introduced in NSW in the section Mittagong - Bowral, in 1888. The last tablet section was Antiene - Grass Tree, which was replaced by Miniature Electric Train Staff 29 April 1959.
The first use of the Webb and Thompson Electric Train Staff system in NSW was in 1891 for the section East Maitland - Morpeth. Assuming the above information is correct, those first instruments would have come directly from the LNWR at Crewe. Miniature Electric Train Staff instruments were introduced by the Railway Signal Co. in 1906 and to the NSWR in 1913 on the Richmond line.
The Electric Key Token (EKT) instrument was invented by A.T. Blackall and C.M. Jacobs of the GWR in 1912. The design was licensed to Tyer & Co.
McKenzie & Holland, Ltd. patented their own tablet instrument in 1896. These tablets (or at least some of them) were square, as were some used in the Tyer No. 6.
CMIIAW, but it is my understanding that the Tablet system was rather inflexible, and if a train was cancelled after the tablet had been withdrawn, it could not be replaced in the same instrument from which it had been withdrawn.
This is true of some Tyer ETT instruments but not others, e.g. the No. 6, 7A and 7 instruments, patented in 1892, '96 and '98 respectively, were "returnable", whereas earlier versions (nos. 1-5) were "non-returnable". NSWR used five variations of the Tyer ETT instrument, including the returnable No. 6. It is quite possible that the majority in NSW were non-returnable, because the cheaper ETS was already in use by the time the returnable versions were developed.