Play- ... d'oh!

I used play-doh successfully to mask and airbrush difficult shapes, but you'd have to paint it right away after applying it. If you don't, 24 hours later it looks like this :

It's pretty much useless now. It's not really a problem since the pieces remove easily.

I tried again with modelling clay. The clay seems to dry slower and shrinks less, causing less or no cracks.
I didn't wait for it to dry though and sprayed the final color : insignia blue.

The letters are impossible to mask and will be done with a brush.