As Iron mentioned a few posts ago, I have a ballistic nylon cover that makes the area look neater and helps keep moisture from dripping onto my avionics. (Rain tends to leak onto that area through the tip-up hinge areas and water occasionally pools on top of the cover.

) The cover was made of water-proofed, ballistic-type nylon (like the material used for some backpacks) and installed by one of my previous owners. The glue and velcro were worn so Louise and Paul cleaned it up, put new velcro on it, re-glued it (with contact cement) to a flange on the sub-panel that's on the cabin side of the firewall during my recent panel overhaul. They also used (black) silicon to ensure a waterproof seal along the engine-side flange. It had previously been attached with small strips of velcro here and there, but the continuous strips all along the panel and longerons make it tighter and neater.
If you look carefully, there are two dart seams sown into the cover at the bend on each side of the panel to allow a smoother curve. Peeling back the velcro allows full access to the back of the panel. You might also note a couple of slots to allow avionics wires have been necessary in my cover.
The cover
Showing a dart and a slot for avionics
Oh, and Louise asked me to mention that she will be doing some more work to polish off my interior and clean-up the black silicone along the back of the cover.