If you have looked at 3D-printed coin storage products, you have probably seen two materials mentioned: PLA and PETG. Both are thermoplastics used in FDM (fused deposition modeling) printing, and both are used in legitimate products. But they are not interchangeable, and the differences matter when your coins are worth hundreds or thousands of dollars.
PLA (polylactic acid) is the most common 3D printing material. It is plant-based, easy to print, and produces parts with sharp detail and clean surfaces. For many applications, PLA is perfectly fine.
Heat deflection temperature: approximately 55–60°C (131–140°F). This is PLA's biggest limitation. In a car trunk in summer, a garage in the southern US, or near a sunny window, PLA can soften and warp. If a storage case deforms, the precision fit that protects your slabs is gone.
Chemical stability: PLA is chemically stable under normal conditions. It does not off-gas harmful compounds and will not react with the plastic in coin slabs. It is safe for direct contact with NGC and PCGS holders.
Strength: PLA is rigid but brittle. It resists compression well but can crack or shatter on impact. Drop a PLA case on a hard floor and you may get a clean break rather than a flex.
PETG (polyethylene terephthalate glycol-modified) is an engineering-grade thermoplastic. It is in the same family of plastic used in food-safe containers and medical packaging, which tells you something about its stability and durability.
Heat deflection temperature: approximately 75–80°C (167–176°F). That is roughly a 20°C improvement over PLA. PETG will not warp in a hot car, a garage, or near a window. For collectors who store their coins in spaces without full climate control, this margin matters.
Chemical stability: PETG is highly resistant to moisture, oils, and most household chemicals. It does not absorb water the way PLA can over long periods, so the dimensional accuracy of the case stays consistent over years of use. The fit you get on day one is the fit you have on year five.
Strength: PETG is both strong and slightly flexible. Rather than cracking on impact like PLA, PETG flexes and absorbs the energy. That makes it more durable for cases that get moved, stacked, and handled regularly.
PETG, across the board. Every SlabGrid display tray and CoinConnex case we sell is printed in PETG, because storage and display products live on desks, shelves, and in vehicles on the way to coin shows, and they need to handle heat, sunlight, and years of handling.
PLA still earns its place in our shop, just not in the finished product. We use it for prototypes and test fits, where its speed and detail help us iterate quickly before a design is locked for PETG production. For the full three-way comparison including ABS, see PETG vs PLA vs ABS.
Both materials are chemically inert and safe for contact with graded coin holders. If you are buying 3D-printed coin storage from anyone, ask what it is printed in and where it will live. A PLA case on an indoor shelf is fine. A PLA case in a car trunk in July is a problem.