4mm or less board that can be plastered over?

[User1234567890]

I need to find some kind of board that is 4mm or less in thickness, that is ok to skim/fill over. Is there any such thing? It's to go over a wooden infill panel above an old door frame, and the frame is not plumb, true, square etc. The wall to the left of the doorway is freshly plasterboarded, so it makes sense to do this and make look a bit neater. Anything reasonably cheap and freely available that would get this done? Thanks.

 

[Wayners]

There are 4mm tile backer boards you can plaster over and the thinnest plasterboard you can buy is 6mm

 

[User1234567890]

Thanks mate, I'll have a look.