Im afraid it was over 8 yrs ago and I cant find any record of it in my email system so I cant remember.
Someone else may be able to help, as I think I got some of it from a Down equipment repair company somewhere in the lake district.
EDIT: it might have been these guys from whom I bought the pertex off the roll.
http://www.mountaineering-designs.co.uk/shop/2/
I may even have got the down on ebay from poland…
EDIT2:
http://www.ebay.com/itm/95-5-White-Hungary-Goose-Down-Feathers-by-the-7-OZ-/221582782056?pt=US_Fabric&hash=item33975cee68
Fabrication was relatively easy as we went with a stitch through design as opposed to the more complicated box method. Getting the down into the cells was a bit messy, but I found just counting handfuls and stuffing them in worked ok.
Mrs Stoner Sr was a flag maker at the time so we had a nice big table and commercial sewing machine to make life easier, but with a bit of space there’s no reason it cant be done on a kitchen table with a domestic sewing machine.