ive done mine aswell, ok so i copied both ben and Wimmy but it does look very nice.
we have all made a covering for the recess out of something fairly solid and robust. iirc Wimmy used some perspex or similar.
i used some thin plyboard and rivited it to the bottom edge then gently steamed it so it could bend correctly then riveted on the top edge. a couple of rivets on each side aswell just to give a better fit. this is only possible with the dash recess removed, which is a pain of a job tbh. the glovebox needs to come out, then you have a selection of 10mm nuts iirc on the front edge and also up the back aswell, which are extermely awkward to get to. you also have to strip the centre of the dash aswell so that it can be removed, a long job, but the end results are worth it. im going to be re upholstering mine this summer as the seude has sagged a little and got a few dodgy marks on
hth