Adding weight to small locos is always tricky. Further complicated in this case by the need to put as much weight over the rear axle (remember that this is only driven on the rear axle) as possible for traction purposes.

I use aquarium plant weight, which is lead strip 6mm wide and .9mm thick. I know that lead flashing is cheaper but using plant weight is more convenient to chop up into small pieces. I sometimes use liquid lead as well (I didn't on this loco) if I can make a 'box' to keep it in place.

The chassis has lead crammed everywhere possible. In the body I've glued lead into the cab, under the bonnet and under the roof (2 layers). Total weight 77 grams. Here's a couple of pics;

A shot of the chassis on its own, the leads are only soldered to the pick-ups as this loco will be fitted with a decoder by its owner (not having any knowledge of DCC I'd prefer to let someone else do that bit!);

The brake shoes are superglued rather than soldered in place, which makes any future maintenence easier.

And finally a couple of shots of the loco finished, ready for despatch;

Right, off to the Post Office!