As a result of comments on earlier posts, I have added this supplement, to describe some variations in lining styles. The GWR used many different styles of lining at different periods, as I was reminded by 'N15class'. Many of these can be reproduced by slight variations of the methods I described in earlier posts.
Before 1881, however, the GWR sometimes used a technique called 'scarfed' lining, which is a variation on 'dropped shadows'. In the period 1864 - 1881, the lining comprised a 1” wide 'pea green' line, bordered on one side by a 1/2” black line and, on the other, by a 1/8” white line - with the added twist that these edges were offset, so that white always appeared to the left and above, whereas black appeared to the right and below.
This more complex scheme, also used by other companies than the GWR, can be reproduced by making use of 'layers' in Photoshop (or PSE), to represent the different colours.
I start by constructing a rectangular panel frame in black - 24 pixels wide. KH1 suggested a method for creating the curved corners and I have adapted this by using the Elliptical Marquee Tool', rather than Paintbrush (hold down the 'Shift' key to constrain the tool to a circle). I use this Marquee tool to mark off circular selection areas, inside each corner, as shown below, and then 'Invert' the selection [menu: Select | Inverse] and use the Paintbrush to fill in the rounded corner, against the selection boundary.
Making Rounded Corners against a selection Boundary
The outside corners can be made in exactly the same way, with selection boundaries set against the outer edge of the corner, and painting in the background colour.
The next step is to create a duplicate layer [menu: 'Layer | Duplicate Layer...' - select 'Background copy' in the box that opens]. Then select the lining shape, on this new layer, with the 'MagicWand' tool and fill the shape with a Pea Green colour (R,G,B = 128,128,0),
Creating a Background Copy
Next, invert the selection, so that the whole of the background on the new layer becomes the selection, and select 'Image | Clear'. This will remove the background from the new layer but there will be no visible change, because the original layer will show through from 'below' (Think of 'layers' as a stack of images behind one another.)
Now remove the selection [select | Deselect] and use the 'Move' tool to move the new layer upwards and to the left. The 'Pea Green' lining will move relative to the black and the background, which are on the original layer. Position it (by eye), so that half the thickness of the pea green band appear as a black 'drop shadow'.
Positioning the top layer relative to the Background
Now we do the same again for the white 'shadow'. Make sure the original Background layer is selected (This should happen automatically if you click on the background) and then make another duplicate layer. select the loop of lining again and, this time, fill with White. (The new layer should have slipped in underneath the top 'Pea Green' layer.) As before, select everything except the lining loop on this new layer and 'Clear' the background. Now 'Move' the White layer into its position above and to the left of the Pea Green loop.
Now you have some 'Scarfed' lining! 'Flatten' the image [Layers | Flatten Image] and it is ready for printing.
'Scarfed' Lining Panel
There are lots of other complications beloved of 19th century designers, such as inverted corners. I've not yet tackled these but would approach them by using the same techniques that I have already described. Always remember that, once you have drawn a complex ornamental flourish, you can use 'Copy' and 'Paste', together with 'Rotate' and 'Flip', to repeat the design in different ways.
At this stage, I'll just wish you good luck