Field Notes.

Engineering and Amazon-margin notes for operators. Written by Dave Lock, plainly and without the agency gloss.

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All Margin IP Manufacturing FBA

FBA · Pillar note The March 2026 Amazon Commingling Change: What UK Sellers Need to Know Amazon retuned how commingled stock is pooled and how the Buy Box rotates across sellers running the same unit. What changed, why it presses harder on white-label margins, and the cases where it stops being a problem. Read the note →

Manufacturing Tooling amortisation and the white-label trap Why a low unit price on someone else’s mould is rarely the cheap option it looks like, and what the tooling maths actually says when you own the part. Forthcoming

IP Freedom-to-operate for Amazon sellers A plain read on what freedom-to-operate means before you commit to a unique product, and where a qualified attorney has to take over from the engineering. Forthcoming

FBA FBA packaging rules that change your design Amazon’s packaging and prep requirements are a design constraint, not an afterthought. The rules that quietly dictate dimensions, materials and unit cost. Forthcoming

Margin When should a UK Amazon seller move off white-label? A decision framework for the trapped white-label seller, built around the numbers that actually decide whether engineering a unique product is worth it. Forthcoming

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