Vossy1
Landlord.
IIRC, the chap from oilybits will quite happily give you the dimensions of the hole needed to be cut for the conical to sit in. 1" ply makes a great base for them (suitably sealed)
EDIT IMO, once you start going over £200 (if you do) it may seriously be worth thinking about stainless
EDIT IMO, once you start going over £200 (if you do) it may seriously be worth thinking about stainless