This is my first instructable and I didn't take to many pictures I'll try to take more in the future but this is so self explanatory that I don't really need more pictures.
Step 1: 6.00€ of Supplies
Black spray paint
Silver model paint
Those cheap little see through waterguns you get for 1.00€
Step 2: Last Step
Spray the water guns black
Now refine the parts you want silver with the silver paint
If you want the guns to look more like metal, take a tissue dip it into the silver paint an very lightly brush over the gun for the metal effect.
Step 3: Final Word
I hope my first instructable was helpful and... Well... Instructive. Maybe there are better ways to do this but it's simple, fast and effective. Don't forget to sand the guns before painting though.