Need some advice, painting on plastic with testors. scratch proof

Hello everyone! So, although I do not paint cars but I've been reading great reviews of the testors paints and thought id give it a go for a project ive been working on. I'm in the process of printing, or painting, plastic items to look like  a promotional item you'd get made up. I am aware that that process is much different but I know I can achieve the look I want with paints!

Now, I prepped my plastic and painted on over my stencil with Testors Enamel Paint and it turned out great, I did airbrush and brush to see the diffrence, the airbrush was much thinner and more even. I waited for it to dry it probably still needs another day to FULLY cure but i took a test one, and it seems to be easily chipped off if scratched with your nail. Now this is an item that undergoes handling, Should this happen? Should I Go over it with a gloss clear coat? Should I switch to Acrylics? Kind of stumped here. Hope I can get some good feedback, Thanks much ^_^