Now all the closure rails: Cut an over-length piece and estimate where the bend will be. Notch the 'foot' of the rail (for FB) and tweek until the angles match. Then crank the 'lead-in'. The above is just laid in line before fixing. When happy trim to length - in this case between the 3rd and 4th sleepers, and add half a PECO fishplate. Make sure that you can join another rail to it, and touch with a tiny bit of solder. Repeat with the curved one. It will be noted that something more finescale would probably use Bullhead rail which is more whippy and doesn't need a fishplate hinge. With the bendy rail added, it should look something like the above. Two things to note: One, I'm running Triang wheelsets through this so the flangeway is quite generous. And two, the dashed arrow pointing to where the rails will be cut to isolate. This means that the 'frog' assembly at Side A will be dead and the rest will be live to the respective stock rail once the gapping is done.
Now the fun bit. The bit that people fight shy of. Blades. Piece of 1" x3/4" timber 6" long. In this case with a saw-cut down it so the FB rail sits flat-ish. Remembering which side the blade is for... clamp down and grind away with a file until you have a nice slope down to about half the depth of the web at the last 3-4mm. Clean it up. That's it. Do this when wifey is out 'cos apparently it's 'not a nice noise'.
FILE AWAY FROM YOU ONLY! Experience says that a return stroke will bend the rail up like a clock spring. Trim the length to a few mil over the length from the hinge to the tie-bar. Repeat with the curved blade. Do keep cleaning up with a small file on all rail cuts and polish before soldering.