Are you using an airbrush? If not, then you are courting disaster. Anyway, first things first: When removing the window masks try not to touch the adhesive surface any more than is necessary for handling. Visualize where the mask is supposed to go and try to get it started correctly the first time around because even though you can remove the thing and start again several times, it is better to get it right on the first go. So, get it lined up and press it firmly against the window, slowly moving from one side (left or right) to the other or from the center out to the edges. If you've got it applied the way you think it should be, then use something firm yet flexible but not pointed to burnish it to the window surface, especially around the edges. I use a guitar pick for this job (the back edge of a standard teardrop shaped pick). It should go without saying that you should then use whatever is your preferred masking tape to cover the other side of the window. At this point I spray the edges with clear (usually semigloss or flat) to seal things up so the black doesn't seep under the tape. Then spray away with the black of your choice (or some other color if you have to be difficult about this!). The most difficult stage comes next: removal of the mask! Don't use a hobby knife blade for this. I usually put a small piece of Tamiya masking tape in the center of the window to be masked so I can more easily remove the mask after painting by poking a little dental-type pick under the mask where that little piece of tape is and lifting the mask. This procedure reduces the chance of scratching the glass when removing the mask. Finally, when this is all done, stand back and admire the thoroughly satisfying and professional looking results of a job successfully completed due to adequate preparation and meticulous execution.
All right, then, I guess it falls to me to be the voice of unreason: Just smash the thing and start with a different project. There is no inherent virtue in perseverance and sometimes it leads to folly.
They are both the Hasegawa kit. I've posted these pictures only to illustrate how good the kit engine can look in these things. Sean can decide to build the thing curbside and it will look great on a shelf. Or he can try to find an engine for the beast.
As you can see, this 2CV has been driven a lot but pretty well maintained:
And the best I can do for now:
I lived in Paris for two years and would be there still if I could have found a way to pay for it. When did your wife's family own these cars? I'm especially curious about the Mercury because a Simca Vedette would have looked much like a Mercury of that vintage.
Now I feel like an idiot. I'd forgotten that I'd seen this advice from you before and even took a bunch of used dryer sheets upstairs to the model zone to use in this capacity. Then I found myself asking, "Why did I bring up all these used dryer sheets?" Mystery solved!