3D printed holes rarely end up round unless you specifically orient the entire part for the hole, which also tends not be the ideal orientation for the part as a whole. Drilling the holes has generally been easier and more precise, especially across the thousands of holes I've needed over the years.
As for the Drill bits, well I'm in Canada, so they obviously exist outside the US, I specifically bought a little set like this one and a simple conversion shows that 7/64" is about 2.75mm as well.
What I was thinking about doing is superimposing the G10 plate over the intel bracket and making markings through the C holes.
I found this Dremel drill bit set on amazon.com, do you think any of these bits will be the correct size and do you think a Dremel tool has enough torque to drill through the Intel bracket?
Although costly (total outlay $30 for Dremel tool and bits) this approach would allow me to cut the corners and drill the Intel bracket.
https://www.amazon.com/Dremel-628-01-Piece-Drill-Bit/dp/B0000302Z3
Seriously though, you should fabricate these brackets and sell them for $30. People would buy them. You can purchase them in bulk from Corsair for $10-15, make a few holes, turn around and sell them for $25-30. You sell 2-3 a day that's some money for not a whole lot of work.
Adding the required shim and these would sell with the demand exceeding supply of the EVGA Hybrid kits.
Pay less for vastly superior performance (with x41, H100i)
EVGA wants $120 for their H55 rebrand.
$60 for an H55 and $25-30 for your kit that's a no brainer.
I think the ones in that kit are just standard drill bits. You can shoe horn them into cutting through things, but they make other bits that work a bit better (different fluting).
Basically it is the difference between this and either of these bits.
Hard to tell though from the picture, so they might be cutting bits.