THE P-TOUCH AND SIMILIAR MAKE GOOD MARKERS FOR TUBES AND OTHER THINGS BUT ARE NOT GOOD FOR CAPACITORS. THE LETTERING IS TOO LARGE FOR CAPACITORS AND OTHER THINGS THAT MAY NEED SOMETHING SMALLER.
Depends on how big your caps are. P-Touch makes labels as wide as 1.5" and uses fonts as small as you like. My calculations show you could make labels for caps as large as slightly less than 1/2 in in diameter - not enough for the bigger ones but good for the medium size and smaller.