No, not some child-like attempt to simulate steel coil loads, just a quick and dirty way to hold the sides in place while the glue dries - the wagon is a Parkside slope sided mineral in 7mm scale. Generally Parkside kits are very good indeed - easy to build, accurate and highly recommended to anyone who fancies putting a toe in the 7mm water. The slope sided mineral, I know from past experience, involves a little more work than most of the range. A fair bit of filler will be needed to get a seamless join in the side pieces - nothing too difficult, but if you don't put a bit of effort in then things will look unsightly.
In the past I've been reluctant to feature much 7mm modelling here, simply because the site is supposed to revolve around my 4mm layout. The idea was to feature the layout because mainstream magazines always concentrate on rolling stock, to think big because the mags tend to think small. In short, an antidote to all those bl**dy BLTs (Branch Line Terminii) and 6 page white metal kettle articles we're bombarded with. However, due to a large amount of e-mail from interested parties I've now relented on that score. I don't know what form it will take (probably a new, separate 7mm section) but for the time being I will drop the odd photo into OMWB to keep things simmering. In a non-kettle kind of way...