I read about a manual method some years ago on the Sony/DBG forums that I still use to this day. I have 6 chars at 350 skill in all tradeskills so I've managed a lot of inventory.
R -- Use the outputfile command to dump a text listing of a mule's inventory, then use a good programmer's text editor like Notepad++ to open ALL the text files and easily search across all your inventory. (Can also dump the contents of housing and guild banks!)
1.) Don't use houses. Houses were not a thing yet when I started doing tradeskills.
2.) Create multiple characters on a single account with each character dedicated to some major tradeskill. These characters should NOT be on the same account as your mains.
3.) Load said characters with tradeskill bags or higher capacity heirloom bags.
4.) Can Use giveitems.mac to partially automate handing off tradeskill items to mules. When you give the wrong item to the wrong mule have that mule put it in shared bank so the correct mule can pick it up and deposit it.
5.) When stacks fill put the full stacks in the mule's bank.
6.) Dump a text file of the mule's inventory to a text file. Name it smartly so it's easy to determine which file belongs to which mule. Use a standard location and format for the text file so they're easy to find and easy to identify. Create an in-game macro button to automatically create these files. I use a button that dumps the file(s) and then camps the character.
7.) Use a good text editor like Notepad++ to open ALL your mule's text files at one time. (Select block of files in Explorer, Right-Click any file, Choose Open with Text Editor.)
8.) Use the text editor's ability to search across all text files for specific items.
9.) BONUS -- A search program like Agent Ransack can also search for specific items across multiple files just as easily as your text editor.
Social button contents:
Line1=/pause 10, /outputfile inventory C:\EQInventory\Account-Character-Inventory.txt
Line2=/pause 10, /outputfile guildbank C:\EQInventory\Guildname-Inventory.txt
Line3=/pause 10, /outputfile realestate C:\EQInventory\Account-Character-Plot.txt