I make these bags myself. I use MDF as a stiffener, so that they won't go out of shape unless maybe they got soaking wet. The outer and inner fabric are waterproof of course but it would be possible for rain to get through the seams if it was left in the rain for any amount of time. I use the traditional turn lock fasteners, but will be experimenting probably with magnetic catches one of these days I think. I either make my bags attachable to the pram with bridges, which is what the black one has, or I use D rings, which is what I used for the green bag. I also use the traditional black handles as used by Silver Cross too, but I have only a limited amount and may not be able to get more.
Cost for these bags is £55 plus postage.
Black hopsack fabric bag.
Front
Interior
Reverse
Green Pram bag for sale
Front
Interior