font files

does anyone know how a font file is structured? im looking to design my own fonts and possibly create a visual basic program for designing fonts. also is there a restriction on the graphic size for each character? as i would like to use high quality images to make a really good looking font

people? someone out there must have a clue how to do this without going and spending £300 on a program like macromedia's font making thing... (and no im not looking for a cheap program that does it, i want to be able to do it myself... please?)