I’ve been using my new tool:
6 mm discs of 0.25 mm plate for the covers over the firing ports, with a much smaller disc on it (made with my RP Tools set) for the hinge — on both sides and the rear. On the sides, their tops are about level with the bottoms of the vision blocks, and all are about 2 mm to the left of the blocks (when viewed). At the back, they are about 6 mm below the tops of the doors and 3 mm from its left edge. On real Piranhas, the hinges can be either at the bottom or at the right, and as you can see, I chose to put them at the bottom because that seems to be the older style.
The ventilator on the roof, between the hatches, was also made with my new tool: first a 4 mm disc of 0.75 mm card as a spacer, with a 6 mm disc of 1.5 mm card on top of that, of which I filed the edges at an angle to make a truncated cone. That I had to do that anyway was a stroke of luck, because I found that the 1.5 mm plate is too thick to punch well with this set — it’s fine if you want a hole in a plate, but not if you want the disc, because its edges will be ragged. That is to say: the two sides were nicely 6 mm and round, but the thickness of the plate between them was ragged and smaller in diameter than the rest of the disc. Anyway, after filing and glueing it in place, I added four bits of 0.88 mm rod around it, because something like that is visible in Trumpeter’s instructions, too.