How do you paint on a plastic barrel?

My boyfriend made me a safe using a barrel and metal for the lid and base.


The barrel itself is a nasty brown colour and I wanted to paint a design on it,





How would I go about making it white? I know primer peels off, does gesso soak in..?How do you paint on a plastic barrel?
I'm sure you can find paint suitable for plastic. Just go to your local art store and ask. I'm not sure if gesso would work because it is a non-porous hard surface. I would say spray paint, but ask the store employees anyway.How do you paint on a plastic barrel?
There is spray paint that is made for plastic. You can probably get it at any major hardware store.