a Hornby track planning set.
This consists of quarter scale plastic pieces of track that can be clipped together jigsaw style to quickly produce a scale plan. Draw your baseboard out on a bit of paper and you can try things out and then read off the part numbers should you wish to build from the Hornby range.
I find this sort of thing much more fun and a whole lot easier than using a computer program to do the same thing. Perhaps for complex layouts where the ability to virtually operate the model is useful, computers have their place but I much prefer templates. Plugging the bits of track into each other or messing around with point plans just seems more organic and natural to me and makes the process more enjoyable.
One thing the exercise has shown is just how small the box is. Some sort of removable fiddle yard/cassette looks to be essential if this model is to work. In the meantime I'm going to move on from the plastic bits and try some photocopied point plans in case the geometry of the SMP hand built track isn't the same as RTR Hornby. At least I have an idea of the challenge now.