I decided to add a few new potions to my game. I opened up my Alchemy tab and entered in the effects, name, ID, weight, etc. I wanted my potions to look exactly like Standard varieties, so I searched for the model m/misc_potion_standard_01.nif. However, when I searched through /meshes/m, I could not find the art file. I figured it may have ended up in a different file location since I changed the install location of Morrowind, but I searched my whole computer for the file and it did not exist. I even shortened the search parameters to "potion" but even then, nothing was coming up.

So my question is this... where the heck do I find the icons/models for potions? o.O

They're stored in .bsa files, like Morrowind.bsa. Extracted files should be on the Construction Set CD.

You can also extract any required files from the bsa files yourself. I use the Fallout Mod Manager's bsa extractor but there are plenty of tools out there that can do it, just have a look around PES, TES Nexus, or Yacoby's ES Search.

Note that both sources have files the other does not, and some files do not quite match up between the two (different format and quality textures, esp). If you extract or copy and something still looks missing, check the other.

You should be able to open the CS, pick any random potion, like Standard Restore Fatigue, give it a new unique ID, and save it as a new object. Now you have a potion that looks exactly like one of the standard potions. Then alter the effects, weight, and display name.