I most certainly approve of making ones own; especially the recycling part of it.
I purchased some, I believe from two dealers, at an Exeter Show a couple of years ago. They were heavy and had the advantage of not being blown away in gales. However, if you wish to make a load in a long gondola those type of barrels can add too much extra weight to the train. So the method shown in a previous post, or a similar to suit your own skills or junk box, is ideal for a wagon load which will have little added weight.
I feel that personally constructed items are more rewarding to have than purchased items. Apart from a passenger car, which has been made into a static diner, all my structures have been built using treated timbers. Some goods loads have been built in the railway workshops.