Thanks guys, compliments appreciated,
but it really is dead easy to do and it lasts as well as the paint bonds itself to the plastic, and doesn't chip off like car paints.
Wash the inside out with a bit of washing up liquid in some warm water, dry with a hairdryer and then warm the shells just a bit to help avoid runs in the paint.
i used a £10 airbrush that i already had, on that egg but i've used the polycarbonate spray cans with equal results on my R/c cars.
Only other tip is to really keep spraying from different angles as you tend to miss bits around the ribbing inside the shell.
If you can disassemble a hopper then you can do this, stock hoppers are so boring and i'm sure someone could be more creative than me