hi

i plan to buy a 9.5mm drill bit, and hand drill two 3/8" lock nuts (8mm thick).

the frame spacing is 126mm. the hub is 110mm. Hence, i need two 8mm (D in photo below).

so, is this a good idea? is it easy to hand drill?

3/8" is 9.5 mm, so all you'll need to do is remove the threads from the nut. It should be very easy.

Don't you have a 3/8" bit?

We don't know your machining skills. Beware of common hazards. Use eye and hand protection. Secure the work well.

Your axel is 3/8? You can buy spacers from many BMX shops like this 3/8" Alloy Axle Spacer 2mm, 3mm, or 5mm SIZES (PAIR) - Planet BMX

i am not in US. i dont see fractional size drill bits here, but i didnt look very hard. so far, i only see metric drill bits here, like, 9.5, 9.8, 10.0 mm, etc.

i dont have much tools with me here. Have to borrow tools.

i have a cresent wrench to hold the nut and an electric drill.

yeah, i need to buy safety glasses.

thanks but...
i am not in US. i dont want to pay international shipping.

I don't know where you are, but Misumi has branches all over the world and sells either stock spacers for around $1 each or custom made from their Chinese suppliers for $3 each. They're for industrial machinery and automation, but I've used parts from them to fix my bike. You can even specify a tolerance of around 0.02mm for the shaft diameter. You need to pretend to be a business though to open an account if you don't have an actual business.