The shield covering the fresh air blower and ducting in the rear of the trunk is made out of some cheap cardboard material. When new, it may look OK but mine had several holes drilled in it from a previous owner and was looking a bit ratty.
Using some 0.25 inch ABS sheet, I cut out the rough shape of the cover. I then positioned it over the original and clamped the base. Using a heat gun, I applied heat as needed to soften the sheet and allow it to be bent to the required profile. Once the sheet was properly bent, I clamped it in place and let it cool.
The old cover is attached to the frame brackets using rivets which were drilled out. The old cover was then placed on the new one and marked the holes and any required notches. The new panel was attached with rivets and trial fitted. Some small adjustments were needed before it could be bolted in place.