On the tug cabin side are strips of metal riveted in place. In 4mm scale, bodgers like me will use cubes of plastic well washed with solvent to take the edges of. In this scale something rather better is called for.
I can't remember where I picked this up from but making fake rivets is pretty easy. All you need is some plastic rod and a soldering iron.
Simply hold the end of the rod near the hot tip and it will melt slowly to form a dome.
Let this cool for a few seconds and chop from the end with a knife - snips squash the rod I found and it's easier to fit into round holes if cut with the knife.
Drill a series of holes, fill with plastic cement, fit the rivets and wash with solvent.
Skillful people will be able to gauge the size of the domed heads but working by eye give acceptable (to me) results.
There are 8 in the photo - I counted them!