A Bill of Materials (BOM) is often described as a “recipe.” While that’s a helpful starting point, it’s also a bit of an understatement. If you’re running a mid-market manufacturing operation in 2026, a recipe isn’t enough to keep your margins healthy. You don’t just need to know that a cake requires flour and eggs; you need to know the cost of the electricity to run the oven, the percentage of flour spilled on the floor, and how many cakes you can realistically bake in an eight-hour shift.
Many businesses start their journey in Fishbowl Inventory by using BOMs for simple kitting—taking Part A and Part B and putting them into Box C. But as your business grows, your “simple builds” inevitably become more complex.
To maintain a competitive edge, you have to move beyond the basic build. You need to master the advanced architecture of BOMs to capture the true Cost of Goods Sold (COGS) and gain total visibility over your shop floor. Here is how you master manufacturing BOMs in Fishbowl to turn your warehouse into a precision-engineered profit center.
1. The Power of Sub-Assemblies: The “Lego Brick” Philosophy
One of the biggest mistakes growing manufacturers make is creating a “Flat BOM.” This is a single, massive list of every single screw, wire, and housing component required for a finished product. While a flat BOM is easy to create, it is a nightmare to manage.
The Problem with Flat BOMs
If you are building an electric mountain bike, a flat BOM might list 400 individual parts. If a single sensor in the battery pack changes, you have to update every single bike model that uses that battery. Furthermore, a flat BOM assumes you build the entire bike in one sitting. In reality, you probably build the wheels on Monday, the battery packs on Tuesday, and assemble the final bike on Wednesday.
The Solution: Nested BOMs (Sub-Assemblies)
In Fishbowl, you can create Sub-Assemblies. This is the practice of creating a BOM for a component (like a “Battery Pack”) and then treating that finished battery pack as a single “part” on the Master BOM for the bike.
The Benefits include:
- WIP Visibility: You can see exactly how many completed battery packs you have in “Work-in-Progress” (WIP) vs. raw lithium cells.
- Modular Updates: If you upgrade the battery’s internal wiring, you only update the Battery BOM. The changes automatically reflect across every bike model that uses it.
- Accurate Scheduling: You can schedule a manufacturing order (MO) specifically for 50 batteries to replenish your sub-assembly stock without needing to trigger a full bike build.
2. Accounting for the “Oops” Factor: Scrap and Yield
No manufacturing process is 100% efficient. If you are cutting circles out of a square sheet of aluminum, the corners are gone. If you are mixing chemicals, some will evaporate or stick to the side of the vat. In the electronics industry, a certain percentage of microchips will inevitably fail testing.
If your BOM says you need exactly 10 square inches of aluminum to make a part, but you actually use 12 square inches because of the “scrap” left over from the cut, your inventory levels will be off by 20% every single time you run a build. By the end of the month, your system thinks you have a full sheet of aluminum left, but your rack is empty.
How to Fix it in Fishbowl
Fishbowl allows you to factor in Yield and Scrap percentages. This ensures that the system “pulls” the correct amount of inventory to account for the waste.
To calculate the true amount of raw material you need to stock, you can use the following formula:
Actual Quantity Required = Net Quantity in Finished Product / Yield %
Example:
Suppose you are a high-end furniture manufacturer. To produce one table, you need 50 board-feet of walnut. However, due to knots, sawdust, and trimming, your yield is only 85%.
Actual Required = 50/.85 =58.82 Board Feet
By entering this into your Fishbowl BOM, the system will correctly deduct 58.82 board-feet from your inventory and—more importantly—apply the cost of that wasted wood to the final price of the table. This prevents your margins from being “shaved away” by unaccounted-waste.
3. The Missing Link: Labor and Overhead
Is your product’s cost just the sum of its parts? For many SMBs, the answer is a dangerous “yes.” If you sell a product for $100 and the parts cost $40, you might think you have a 60% margin. But if it took a specialized technician two hours to build it, and that technician costs you $25/hour, your real margin is significantly lower.
Using Service Items on BOMs
Fishbowl allows you to add Service Items to a Bill of Materials. These aren’t physical parts that sit on a shelf; they are “placeholders” for labor, machine time, or even outsourced processes (like powder coating).
Consider this scenario:
You have a CNC machine that requires a $200 specialized drill bit that must be replaced every 100 hours of run time. You also have a technician operating the machine. By adding these as “Service” parts on the BOM, you can:
- Assign a “Labor” cost per unit.
- Assign an “Overhead” cost (for electricity or machine wear-and-tear).
- Ensure your Total Manufactured Cost is reflected accurately when the finished good hits your warehouse.
When your Fishbowl data flows into QuickBooks or Xero, your accounting team will thank you. Instead of seeing a massive, unexplained “Payroll” expense at the end of the month, they will see that labor cost correctly allocated to the Value of Inventory.
4. Mastering Revision Control
Manufacturing is rarely static. You find a better vendor for a bracket; you realize a certain screw is prone to stripping and swap it for a sturdier version. This is where Revision Control becomes critical.
If you have a team of five people on the shop floor, and three of them are using an old printed BOM while the other two are using the new one, you are going to end up with inconsistent products and a massive “RMA” (Return Merchandise Authorization) headache.
Fishbowl’s “Effective Date” Feature
Within the Fishbowl BOM interface, you can manage versions. You can set an “Effective Date” so that the system automatically switches to the new “Version 2.0” BOM on a specific day. This prevents “Version Drift” and ensures that every Manufacturing Order (MO) created after the cutoff uses the updated parts list.
Pro-Tip: Use the BOM Notes field to document why a change was made. In 2026, traceability isn’t just for food and pharma; it’s for any business that wants to maintain high-quality standards and avoid liability.
5. Automating the “Shortage” Conversation
The ultimate goal of a master-level BOM is to let the software tell you the future. If your BOMs are accurate—including sub-assemblies, scrap rates, and lead times—Fishbowl becomes a crystal ball for your purchasing department.
The Shortage Report
When you “Issue” a Manufacturing Order in Fishbowl, the system performs a Shortage Check. It looks at every nested layer of your BOM. It doesn’t just check if you have the finished battery pack; it checks if you have the lithium cells to make the battery pack.
The “Auto-PO” Power Move
By combining a Master BOM with Reorder Points, you can utilize the Auto-PO function. If a large order comes in for 100 E-Bikes, Fishbowl can automatically generate Purchase Orders for every nut, bolt, and sub-component you are missing to fulfill that specific build. This eliminates the “Wednesday Panic” where production stops because someone forgot to order a $0.05 washer.
Conclusion: Precision In, Profit Out
Mastering manufacturing BOMs in Fishbowl is a journey from “guessing” to “knowing.” When you take the time to build sub-assemblies, account for scrap, and include labor costs, you aren’t just “organizing your data”—you are protecting your cash flow.
In a high-velocity manufacturing environment, your BOM is the foundation of your entire operation. If the foundation is weak, your scheduling, purchasing, and accounting will all eventually crack. But with a precise, master-level BOM architecture, you can scale your production with confidence, knowing that every unit that leaves your dock is priced for profit.
Need a hand auditing your current BOM structure? At LilyPad Applications, we specialize in helping manufacturers take their Fishbowl setup to the next level. Whether you need custom reports to track WIP or help structuring complex sub-assemblies, we’ve got the boots-on-the-ground experience to help you succeed.