What a great idea for a forum thread. The Northern Districts Model Engineering Society is just down the road from where we live. We've often thought we should cycle down there on an open day and have a look.
Seeing this forum has almost certainly moved that forward.
http://www.ndmes.net/page1.aspx
EDIT; So we made that trip last Sunday. What we found was a folded 8, multi gauge track of about 500-600 meters. 2 1⁄2" (64 mm), 3 1⁄2" (89 mm), 5" (127 mm) and 7 1⁄4" (184 mm). A well shaded picnic and BBQ area, 20-30 members volunteering on the day and about 100+ interested visitors watching 5-6 locomotives circulate.
Public open days are last Sunday of the month. Entry was AU$10 and you could ride as many times as you wished.
There is a large club rooms that had a mill and lathe that would be larger machines than many of the members may have room for in their home workshops. Thanks to Peter for showing us though.
Here's a link to some more pics and description.
https://goo.gl/photos/pF9yNkaYBNXZ6Eej8
