I paint for a living. Aluminum is a none ferrous metal. That means a magnet wont stick to it. You need a none ferrous metal primer. You 1st need to scuff the parts and mask where the paint is not needed and spray apply the parts. Get a cardboard box ,cut a hole in it for a hair dryer and hang the parts inside. Bake those guys until their good and hard. Check for hardness after cooling. Next your ready for your enamel. Sand those guys with some 200-300gt paper and apply your enamel. Rattle can enamel will work but automotive is much nicer and more durable. Let it dry to the touch between coats. Bake those parts hanging in the box. Dont use the oven in the house. Stink out...
Shart Guard .......Use it !
Pink Powerwheels Barbie trike
Wamo Big Wheel with a solid trikecycle front tire
Mini bike 3hp Briggs and Stratton with cambells soup can exhaust
Schwinn stingray with coaster brakes
1985 Crash and Burn champ
1st place National Endo Championship