I need one bit of information 
this is gay but hey i dont have a gauge so i dont know.
For a 2 1/16 gauge, what is the size requirements of the hole in a pod?
Mr. Obviouse would say 2 1/16 but im just not sure :?
It all depends on the size of your gague your getting.
Check out Autometer.com for Gague Sizes.
Here maybe this will be more clear!! im looking for the “??” dimension for the 2 1/16" gauge.
hm If “A” = 2 5/16" then “??” is 2 1/16" ?? right??
Acording to my Oil PSI Gauge I have in my hand yes.
If you plan to make a custom pod, make the hole a little less
than 2" and then slowly sand/bore it out to fit your gauge perfectly
Ok, just make hte pod with no holes, when you get your gauge measure it and drill out the hole 1/16" smaller diameter than the gauge and shove it in there.