BOM Cost Calculator.

Build a BOM cost calculator for Trailhead Snacks, a 15-person granola bar and trail mix producer in Boulder. Layout: a working calculator, not a dashboard. The left panel lists 10 finished goods, each row showing product name, cost per unit, and a margin badge; selecting one drives the rest of the screen. The center panel is the cost workspace for the selected product: editable inputs for batch size in units and selling price per unit at the top, then the bill of materials table with component, quantity per batch, unit of measure, unit cost, and extended cost, followed by labor and overhead lines from the product's assigned production line. A summary block totals ingredient cost, packaging cost, labor, overhead, batch cost, cost per unit, and margin percent, with a small donut chart of cost composition beside it. The lower region has two tabs: Price Register, a searchable table of all 35 ingredient and packaging items with unit cost editable in place and a last-changed note; and Margin Watch, a table of all 10 products with cost per unit, price, actual margin, the 35 percent target, and variance, paired with a bar chart of margin by product against a target reference line. Data: products like Peak Oat Bar, Honey Almond Bar, Dark Chocolate Trail Mix, Sesame Crunch Bar, and Maple Pecan Granola. Seed 35 components: oats, honey, almonds, dark chocolate chips, dried cranberries, peanut butter, sea salt, film wrap, display cartons, case boxes, and similar, with unit costs from $0.02 to $9.80. Two production lines, Bar Line and Mix Line, each carry a labor rate and an overhead rate per batch. BOMs run 5 to 12 components each. Plant the story: recent price rises in honey and dark chocolate have quietly pushed three products under target, with Dark Chocolate Trail Mix down to a 22 percent margin, Honey Almond Bar at 29, and Maple Pecan Granola at 31, while everything else sits above 38. Behavior: everything recomputes instantly. Change the honey price in the Price Register and every product using honey updates its rollup and margin badge at once. Margin badges: green at or above 35 percent, amber 30 to 34, red below 30. Batch size and price edits persist per product, and read-only visitors still see the full worked example. Visual identity: use an ocean cyan accent for primary actions, chart emphasis, and active states on a clean light neutral base, with a crisp, precise spreadsheet-killer feel.