How can I prep/paint the inside of a gas can?

I've got these old red Blitz gas cans. I picked them up for a song, but they've got some light rust inside and out. I'd like to prep/paint them inside, so I don't have to worry as much about sucking in rust into my fuel filter. Any thoughts? What would I use to treat the inside with? After that, how could I paint the inside?

 

There are companies that make coatings specifically for gas cans. The hard part is the prep. One method I'd heard of is putting a ton of steel BB's into the can and shake til your arms hurt. Try to clean all the loose stuff out as best you can then you pour the coating inside the can and do the same thing, shake the can and hold it at all weird angles so the coating covers the entire inside of the can. I'd always use a strainer though, sometimes those coatings fail (mainly because the prep is hard to do) and then you can have paint chips in your gas.

 

buy some KBS brand gas tank liner, they come in kits from KBS, Kream also makes a kit but KBS is better