Dash panel fix (radio opening)

I am looking for suggestions on the best way to refurbish a dash radio opening which has been cut much bigger than original.  I would like to use a factory radio but the p/o put an aftermarket radio cassette player in and left a large opening. I am wondering if anyone has restored the panel to a somewhat stock condition somehow or has used a kit to re-adapt a factory radio to the larger opening.  thanks  -  dave

I used textured ABS plastic and made a overlay panel

John, I think I'll try the abs plastic method Carl suggested first and if that doesn't turn out well I will definitely get back with you, appreciate both responses.

I have the same problem. Is the damaged area a separate piece of the dash assembly? If so, can it be removed and replaced with an intact part? Probably a major project.

Thank you. It seems I will need to purchase an other dash. Sadly I am a perfectionsist, so patches usually don't work for me. thx Karl