Truly custom font in Tkinter

I am making an interface in Tkinter and I need to have custom fonts. Not just, say, Helvetica at a certain size or whatever, but fonts other than what would normally be available on any given platform. This would be something that would be kept with the program as an image file or (preferably) Truetype font file or similar. I don’t want to have to install the desired fonts on every machine that is going to use the program, I just want to carry them around with the program in the same directory.

Gallery of installed fonts

I want to view the fonts that are installed on my system. Specifically, I want the client-side (fontconfig) fonts, not the old-style X11 bitmap fonts on the server (for which xfontsel does an adequate job). I guess what I’m looking for would be called a font viewer or font gallery. I want to see a bit of sample text for each font, ideally configurable sample text.