While looking for a way to mount gauges I decided to make an entire surround for the OEM gauge cluster that also had room for four gauges. This way my gauges are all mounted uniformly and look like they were intended to be there.
It is bare aluminum, but can be polished, painted, or powdercoated (by the end user) to give more contrast if desired. Flush mount pem studs hold it in place so you don't see hardware if it's painted (unpainted you can see the difference in color of the back of the stud). Comes with the studs pressed in.
CAD rendering is below. Gauges on left are prosport premium, top right is regular prosport, bottom right is an AEM guage. Outer bezel of the AEM gauge is 2.36" and is about the maximum. Prosport are 2.27" and have a little more clearance. Anything bigger than 2.36" will likely have interference with the gauge above it unless that one is smaller. Gauges are 2.44" center to center so you can measure your gauges if you have questions about whether they'll fit or not.
Pricing:
5 People: $55
10 People: $40
15 People: $35
20+ People: $30
1: Dodgy Tim: Cutouts
2: Joseph: Cutouts
3: Wirenut: plain
4: SnyderJD: Cutouts
5: BlWalker: Plain
6: Fastzrex: Cutouts
Pricing is the same for one with qty-4, 52mm cutouts or for a panel with no cutouts.