George,
In this instance pattern making refers to making a template for either cutting around, or making a fibreglass mould from, or sand casting etc. See link:
http://en.wikipedia.org/wiki/Pattern_(casting)

They are likely to use a hard wood, and need to be accurate. Hence the question from ploughex. Also, end mills have a helix shape.

Ploughex,
I've machined 6mm aluminium using a TCT cutter in a cnc router and occasional WD40 spray. TCT cutter was cheap (~£4), did about 1 hours worth of cutting, and was bin fodder afterwards. But it made the one piece I needed.