You guys shamed me into it, I removed the map sensor today and will mill a cover for it.
Auto Gear, The machine turning on the plate on the manifold was done with a kit from Eastwood. They come in 1/2" or 1" diameter and appear to be some sort of rubber impregnated with various compounds. I did mine with the 1/2" diameter roll and the most difficult part is maintaining the spacing for the overlap. I did mine in a milling machine so indexing was easy and accurate but still easy to screw up, ask me how I know
I was getting the hang of it by the time I made the plate on the manifold because I made all the plates for my custom dash.
I wanted to carry the machine turning into the engine compartment so I continued the 1/2" circles and 3" circles on the stainless steel firewall.
The firewall I did with 3" scotchbrite pads. I laid out the circles a row at a time with a magic marker and used the mill like a drill press and just laid the scotcbrite pad in the circles. It took a bunch of pads though, stainless is tough.
Also, when doing the 1/2" circles on aluminum you have to get the speed right, to fast and it will burn the aluminum, to slow and it doesn't cut well. I forget what speed I ran it at but it was around 600 rpm.
I used a mix of water and wd40 for coolant and dabbed it on with a brush. I could only get around three or four circles before the rubber roll would need to be dressed because it seems to load up.
I would dress it with 220 grit adhesive backed sand paper stuck to a piece of flat stock that I could just lay on the mill table and bring the spindle down to touch the paper that way it would dress the rubber roll flat so you get a clean circle.
It is very time consuming, so patience is a virtue