You have to be careful how you secure that and similar products in some circumstances ,I believe it is more the adhesive used but some can swell up over a period and split a model. I found that unlike lumps of lead the very fine balls of metal ( tungsten ?) do live up to the their liquid description very well and if not secured will escape from the tiniest aperture which can cuase problems if it gets unseen on to track and points. I used to it to good effect to completely fill the body of a Tri-ang Railways continental range snowplough, rewheeled with some bogies from a US box van it does a reasonable job of acting as a twig clearer on the garden railway when being sent around as the first train for a couple of hoirs
junk bins at a show .
If you still have a Tri-ang plough with its original ?wings? though keep it original, they got lost or broken so easily that the rarity of a complete one makes them quite valuable in the collectors market, so valuable that it is now possible to obtain new replica wings.