The usual answers are both wrong. "Yes, PLA is corn based and totally safe" is wrong. "No, layer lines are full of bacteria, never let one near your food" is also wrong. Here is what is actually known, what is not, and a position you can defend.
What regulators actually require
There is no such thing as an approved list of materials you may print a cookie cutter from. That is not how food contact regulation works anywhere.
In Australia and New Zealand, food contact materials fall under the Australia New Zealand Food Standards Code. Standard 3.2.2 requires that packaging and materials used by a food business are fit for purpose and do not cause the food to become contaminated. Standard 1.1.1-10(11) requires that substances in contact with food do not pose a health risk. There is no list of permitted plastics. It is a risk based obligation on the business to be able to show that what they use is safe.
The United States and the European Union work the same way in principle. They regulate the finished article and the substances that can migrate out of it, not the manufacturing process.
Two things follow from this:
- If you are baking at home, none of this applies to you. Food contact regulation applies to food businesses. Nobody regulates your kitchen.
- If you are selling biscuits commercially, the obligation is yours and it is to be able to justify what you use. See can you sell 3D printed cookie cutters.
The layer lines and bacteria argument
This is the serious objection and it deserves a serious answer rather than either dismissal or panic.
The claim is that the microscopic grooves between layers give bacteria somewhere to hide that normal washing cannot reach. The mechanism is plausible. The question is whether it has been measured.
There is one directly relevant peer reviewed study: Bacterial Biofilm Growth on 3D-Printed Materials, Hall, Palmer, Ji, Ehrlich and Król, Frontiers in Microbiology, 2021. It grew biofilms of E. coli, Pseudomonas aeruginosa and Staphylococcus aureus on eight FDM printed PLA polymers and measured the result.
What it found is more interesting than the folklore:
- Biofilm growth depended on surface structure and on how water repellent the surface was, not simply on the fact of being 3D printed.
- Highly structured surfaces, carbon fibre filled and wood filled PLA, supported more biofilm. So did the most water repellent one, soft PLA.
- Metal filled PLA showed markedly less biofilm than the others, because the metal is antimicrobial.
What that study does not do, and what nobody appears to have published, is measure a printed kitchen utensil that is washed after every use. The study grew biofilms in culture on submerged samples, in a medical device context. That is a much harsher test than a cutter that touches dough for a few seconds and then goes into hot soapy water.
So the honest statement is: the mechanism is real and measured, the extrapolation to a washed cookie cutter is not. Anyone telling you either that it is proven dangerous or proven fine is going beyond the evidence.
The brass nozzle question
Most 3D printer nozzles are made from free machining brass, which contains a small percentage of lead by design because it makes the alloy easier to machine. The concern is that some of that lead ends up in the print.
The honest position: a stainless steel nozzle costs about ten dollars, removes the question entirely, and prints PLA and PETG just as well. If you are printing things that touch food regularly, fit one. Not because the risk from brass has been shown to be significant, but because the cost of removing an unquantified risk is ten dollars.
The additives question
Virgin PLA is not the problem. The pigments, plasticisers and processing additives in a specific spool of coloured filament are proprietary, undisclosed, and not tested for food contact. That is a genuine unknown and it applies to every colour of every brand.
If it matters to you, natural or uncoloured PLA has the shortest ingredient list.
Coatings
Food safe epoxy resins exist and will seal the surface. Two problems for this particular use:
- A coating thick enough to seal layer lines is thick enough to blunt a cutting edge that is only 0.4 mm at the tip. You will end up with a cutter that crushes dough.
- Coatings need mixing correctly and curing fully. A partly cured epoxy is worse than no epoxy.
Coating makes sense for a printed cup or a mould with large flat surfaces. It does not make sense for a cutting edge.
The argument nobody makes properly
Most of this debate treats a printed cookie cutter as though it were a permanent kitchen tool that has to survive decades of use, like a stainless steel one.
It is not. It costs about 20 cents of filament and an hour of machine time that you were not otherwise using. That changes the calculation entirely:
- Contact is brief and the food is then baked. A cutter touches raw dough for a second or two. That dough then goes into an oven at 180 C for ten minutes, which is well beyond what any surface bacteria survive.
- A cutter you are not sure about gets replaced, not scrubbed. If a cutter has sat in the sink with raw egg dough on it overnight, print another one. You cannot do that with a bought cutter, which is why the hygiene standards for bought cutters have to be higher.
- Most cutters are used a handful of times a year. A Christmas tree cutter works one weekend in December. The cumulative exposure is not comparable to a chopping board.
- Print one per project if it matters. Making biscuits for someone with a serious allergy, or for a commercial order? Print a fresh cutter for it. At 20 cents, a single use cutter is a reasonable thing to do, and that is genuinely not an option with any other kind of cutter.
So what should I actually do
For home baking, which is nearly everyone:
- Print in PLA or PETG from a reputable brand
- Fit a stainless steel nozzle if you print food contact items often
- Wash straight after use in warm soapy water with a brush, never the dishwasher for PLA
- Replace a cutter that is stained, scratched, warped or that you left dirty
- Do not use one to cut anything that will not then be cooked
For selling biscuits made with printed cutters, do all of the above, keep the cutters for that purpose only, replace them on a schedule rather than when they look bad, and be able to explain your reasoning if asked.
For selling the cutters themselves, read can you sell 3D printed cookie cutters and do not claim the item is certified food safe, because for an ordinary FDM print that claim cannot be supported.