They are all based with a 15cm frontage..I forget which set of rules I had in mind to use (it was over 6 years ago)
The slingers got 1/2 the frontage, the scorpians 1/3 but when it came to the archers i was loosing a bit of intrerest and based them so that they all had a 1 cm spacing between the figs....after that it all got confused so the project was binned.
The bases are the sections from folding 2 meter rulers...and each cohort is based in 4 lines.
The only Airfix figs I used were the archers from the set...but the set does
scrub up pretty well.