Thanks guys! I've regrouped to the point where I wanted to tackle the scribing again. I have a scribing template set of common shapes for the little circles and ovals but I didn't have one that matched the shape of the bottom hatch. So I decided to cut a hatch out of brass sheet and either use it as a glued-on piece or as a scribing template. I drew a straight line on a small piece of brass to serve as a guideline.
I printed the drawing that Wojtek posted to approximately 1/48 scale using the distances between panel lines as a rough guide. I glued the drawing on the brass using white glue and set that aside to dry.
The shape was cut out using scissors. The edges are a bit rough but this can be tamped out.
I smoothed out the piece on a piece of glass using the blunt metal end of an x-acto knife handle.
I glued the hatch onto the bottom of the fuselage using two small spots of CA glue. If it sat down perfectly, I could be done with the hatch. If not, I could scribe around the brass hatch and then pop it off, which is what I chose to do. I scribed around the hatch with a sewing needle chucked into a pin vise and pried off the hatch afterwards.
Clean up of the scribed line consisted of a repeated cycle of sanding, brushing off the excess plastic with a stiff paint brush and then lightly rescribing with the needle. Towards the end, I used Tamiya Extra Thin cement to dissolve any little plastic burrs that were left.
The bottom was primed with thinned Mr Surfacer 1000 to check my results.
I now felt brave enough to tackle the multiple small hatches and ports on top of the fuselage. I used a combination of three different scale drawings, which all had slightly different interpretations of the number of hatches on top. Guidelines were marked in pencil and I made sure that I taped the template at each location securely (very important!!!).
After all of the template scribing was finished, I cleaned the work up using the same cycle as the bottom hatch. A coat of primer is used to check my work.
With the scribing work done, I can start joining the major parts together. The wings are still being worked on. I found the need to shim one of the engine nacelle mounting rings.
That's all for now. I should be able to do a lot more work on the Nachtjager since this will be a long weekend for me!