If you wanted to pick one representative method of carrying goods on the railway system throughout its history then in my opinion it would have to be the humble barrel. Simple yet incredibly versatile. They came in a wide range of sizes and qualities depending on what was being carried and stored in them - whether dry goods or liquids. Therefore any railway being modelled which runs even just a few wagons should have some barrels to complete the scene.
These barrels are made using the Slater's product but with hand-applied hoops. Different conditions from new to old barrels can be represented by varying the colouring and weathering of the barrel and also subtle changes to the hoop colouring; new barrels have hoops which have a suggestion of new rust, old barrels have blacker hoops. Stencil markings can also be added to choice. 30 barrels as above, completely finished, costs £66 plus P&P. As a guide, approximately 15 barrels would cover the floor of a typical open wagon.