Cut holes on the console for the tachometer and voltmeter. For other engine info I'll use the display inside the fish finder.
I cut the smaller hole using a hole saw, and the bigger hole using the dremel hole cutter.
Did a few practice runs on a shoebox to make sure I set the cutter correctly.
I've found that a good digital caliper is indispensable for a project like this. I've used it to measure many things, like the size of screws, holes, wires, thickness of boards, etc. A very good investment for $10 at Amazon.