Some basic questions on wave guides

When it comes to wave guides on tweeters, I have very little knowledge. I would like to know more.

What is the typical profile of a wave guide? Parabolic? elliptical? exponential?

Do most people fabricate their own, or do they buy them?

Is there a thread on this site which covers the basics? or perhaps on another website?
 
Firstly, I'm assuming you are talking about a dome tweeter. Typically a compression tweeter is used, however a dome can also work.

Oblate spheroidal has been shown to function practically toward spherical radiation, as a conical waveguide would theoretically do.

All the information is here on this site. Unfortunately it gets pushed back a little over time. Geddes on Waveguides

Many make their own, some buy but the offerings are more restricted. There are some basic commercial offerings available for domes.