I think I know what type of holders you're talking about. You will probably find a smaller one that will work in your local auto parts store. Places like Home Depot or Lowes or even your local hardware store probably have them too. Some have wire pigtails so you'll need to splice your 18ga wire to one of them, but as long as the wire on the holder is 18ga or larger (lower #), you'll be fine. Just get the right size fuse.
where can i find an inline fuse holder that goes can hold a 14 gauge wire? ive been finding lots but all of them are for amp installs and so are around 4-10 gauge.