Repairing MDF shelf finish

Does anyone have a good technique for repairing the plastic finish on an MDF shelf?

I have a SolidSteel rack and one of the shelves has a ding in a very noticeable place. The plastic coating has been knocked off, but the underlying particleboard is OK.

I'm thinking there must be some product that would adhere to the particleboard and could be smoothed in and made to match the existing plastic, and then painted black when it hardens. Any suggestions?

Thanks - David