Japanese doesn't use an alphabet, so to do letters you have to transliterate the pronunciation of the acronym. So "SFP" would be:
esu efu pii
The whole name transliterated into Japanese would be:
supuringu fohdo paakasshon
(by the way, the dots just separate the words; if the words are separated some other way [i.e. on different drums] they don't need to be there)
As for large graphics, it is somewhat difficult to do well on a computer, but you can get the basic shape easily, and then do the rest by hand. If you can see the above, then you should be able to copy and paste it into Word or Wordpad to play with the font, and bump up the size. There are lots of unicode fonts you can download and install here: Japanese Unicode Fonts
All you need to do is find a font you like, print it out big enough so that you can draw a grid over it, then draw an enlarged version of the grid at whatever size you want and use it to copy the outline of the characters. Then you can paint it however you like!