Many thanks for your kind words, Des, Bud, Ernie and Rick!
Still looking for a suitable way to make the radiators for the Viper version, I made another attempt today.
I made this little jig:

Then I cut a 0,1 mm sheet in 12 pieces 2x4 mm and 12 pieces 1x4 mm. I took one 2x4 mm piece and glued it in the corner of the jig with white glue to keep the geometry. Afterwards I just glued the pieces one by one on each other and ended up with a sandwich looking like a comb when looking from the side.
Then I cut it in two halves and after sanding and cleaning I got this:

More cleaning will be necessary but I think it could look satisfactory once fitted:

Cheers!
Ondra