EU Fabrics 12oz Heavy Duty Denier Fabric | Cordura Canvas Fabric with PVC Backing for Sewing | Polyurethane Waterproof Outdoor Upholstery Fabric by The Metre - Black 1 Meter x 150cm

This material is plastic backed, not quite what I wanted but adequate. Reasonable thickness.

Not tremendously thick, but the Denier rating will tell you that. The inside is rubberised, which presumably provides the watertightness, and it doesn’t stretch, so easy to sew. Made a bag for a folding bike, and my domestic sewing machine coped well with it.