Additive is a tool, not a religion
There are jobs where printing is clearly the answer, jobs where it clearly is not, and a band in between where it depends on quantity. Being straight about which is which has cost us individual orders and earned us long relationships.
Quantity eventually wins
Printing has near-zero setup and a fixed per-unit cost. Injection moulding has enormous setup and a per-unit cost measured in paise. Those lines cross. For a simple part the crossover is often somewhere between five hundred and a thousand units. Past it, we will tell you to go and get a mould quoted.
Safety-critical load paths
If a failure hurts someone, a printed part needs to clear a much higher bar than a visual check. Anisotropy, layer adhesion variation and internal voids all make certification difficult. We will print the prototype. We will not pretend the prototype is a certified component.
Anything that must be food safe
Layer texture holds bacteria in ways that are difficult to clean, and most filaments carry no food-contact certification. PLA also deforms at dishwasher temperatures. There are better manufacturing routes and we will point you at them.
Simple geometry in sheet or bar stock
A flat bracket with four holes is faster and stronger laser-cut from steel. If your part could be made by cutting stock, cutting stock is usually the better answer. Printing earns its place where geometry is complex, not where it is convenient.
Very high temperature service
Above roughly 120 degrees continuous, our material range runs out. Specialist high-temperature polymers exist but need equipment we do not run. We will refer you rather than sell you a part that will creep.
What this leaves
Complex geometry, low to medium quantity, fast iteration, customisation per unit, and parts that would otherwise be impossible to make. That is a very large space, and it is where printing is genuinely unbeatable.