I have what I thought would be a basic problem, but have as yet found no information.

All I want to do is plug a hole

On one of our parts, we must make multiple bores to acheive the internal geometry that we want. Some of these bores must then be plugged to prevent air leaks, fuel leaks, etc (it's a TBI throttle body, and the passages are fuel passages and IAC passages).

I was envisioning using something that looked like a miniature freeze plug, and whether it be made of steel, brass, or aluminum I don't care, I want the easiest and cheapest solution. I was also thinking of lead (or something similar but less toxic) that would be easy to press in and maintain a good seal.

this seems like a common issue, so surely I'm typing the wrong words into google!