Spray Can enamel???    Can you explain how you do this Gav?

Sure mate...

get yourself a piece of scrap cardboard and poke some holes in it with a sharpened pencil ( or get an adult for this bit). Poke the globes through so the glass domes stick out the top and spray the domes the desired colour.
 Let this dry - the longer the better, and if you are not too rough with them then the paint doesnt come off when you put them in the machine