The hill material is 50mm thick DOW Floormate by Sheffield Insulation. You can buy it online, but this means buying quite a bit - eight sheets, each 2450mm x 600mm x 50mm. With VAT and carriage this runs in at £123.00 a shot, but time is short and I had to bite the bullet. This job uses about half of it, though quite a bit is 'uncut filler'.
I cut the sheets in half with a normal saw (into 2 x 4s), laid some pieces on my table and began to mark out the forward slopes with some basic lines.
After remarking a wavy front edge I cut them vertically with a coping saw, marked out the top contour 3" in, then cut the slope by cutting on the angle between lower front edge and the contour line. This method gives a fairly uniform slope.
Coping saws are an essential, fairly cheap, tool for this kind of thing as you can vary the angle of the blade within the saw bow. In this case I shifted it through 90 degrees.
Once I had done the first contour - all 20 feet of it - I started on the summit pieces in a similar manner.
Once the cloth was thrown over it, the lakeside was added with a few trees and a few troops it began to look quite good. I still need to paint 36 Gallic cavalry and 48 hastati before Triples, and several units will need basing, but all is well in hand now. Also, my table is only 12 feet long and the table for Triples will be 14 feet, so imagine, if you will, two foot more hill between the central 'summit / knoll' and the hill on which the Numidian cavalry stand.
I hope that this set up meets with the approval of those who know this battle.