Duncan, as I explained earlier the figures come from an outfit, ModelU, who will 3D print them to your chosen scale. I worked out what the height of the figure would be for different scales, cut a piece of wood to that length and moved it around the engines to get a feel for what a figure would look like against them. I didn’t want the figure to be so small as to be insignificant so discounted 1/32nd and 1/35th, and I didn’t want them so big as to run the risk of becoming too dominant and hence the main subject, such as 1/12th.
I decided that 1/19th looked just right so I had them printed at that scale. 1/19th isn’t as odd as it sounds, it is a commonly used scale for military figures where they call it 16mm.
If you want to buy 1/12th scale figures the best source are doll’s house suppliers. I have used resin doll’s house figures a number of times over the years, mainly as there is a wealth of detail accessories available to suit.