Bass:
You don’t know what I tried ONCE but here goes:
Just like at my job, I created an inventory master and bill of materials for every fly pattern I tied which in my world is easy since I don’t tie patterns, but rather generic flies where I just vary the colors & sizes of hooks.
For example I tie a size 16 Sulphur Thorax dry fly so the bill of materials was:
(1) - Daiichi 1180 hook size 16
(1) - Foot of Gudebrod 8/0 Lt Yellow Thread (Inventorying wire for security companies taught me this is IMPOSSSIBLE to get right)
(1/100) - of a package of light grey Hi Viz
(1/100) - of a package of Yellow Microfibbettes
(1/200) - of a package of Superfine dubbing
So if I tied a dozen Sulphurs, I plug 12 in to my “billing” system and my inventory would be depleted 12 hooks, 12 feet of thread (or about 15% of a spool), 12/100 of a package of Fibbettes (or about 10%), 12/100 of a package of Hi Viz (or about 10%) and 12/200 of a bag of dubbing or 5%.
While this system had the advantage of automatically depleting my inventory once I set up all of the bills of materials; it was hardly exact just like the real word of inventory control in an environment where you are USING inventory to complete a job versus selling inventory, as in a retail environment. For example, in the real world we were always long or short on wire or other consumables we didn’t have on the bill of materials. (Notice I didn’t include head cement, glue, wax, etc).
But if you try the retail model in a fabrication environment, you spend all of your time doing cycle counts and inventory adjustments because you have no automated or accurate way of keeping track of what you use without looking and counting which to me wasn’t worth the effort when a quick look-see in a few drawers or Rubbermaid containers accomplished the same thing in WAY less time.
It helps that I pre-plan the flies I plan to tie by making a list first, at the beginning of “tying season”. And I also tie a minimum of two dozen of every fly I tie. This REALLY helps me manage my inventory.
My inventory control system now, consists of an order process which is me sitting at the computer and thinking, “hey, I need to tie some beetles”
Then I check my inventory, which is me walking down to the basement, opening a few drawers and saying, “hey, I need to order some foam sheets”.
Then the order process begins, which is me ordering some foam on line along with a few extra sheets just in case.
And in a day or two when the foam arrives, I check the inventory for the next pattern I plan to tie.
Maybe too simple and uncomplicated for some folks, but I’d rather develop a system for my pantry then my fly tying stuff. Somehow buying a can of Green Giant Nibblets Corn at the market when there is 12 at home, bothers me a whole lot more than 6 packs of yellow Fibbettes. 
Have fun!