You have an enormous amount of choice when it comes to the type of filament you use to make your 3D prints. Not only are there a decent variety of basic material types, but infinite mixes and variations within and between those types.
Yet, these days most people print with PLA, and that’s perfectly fine. It’s versatile, easy to work with and affordable. But in some cases, PETG is the better choice, and just about any modern printer should handle it with ease. But, where and when should you use it?
Outdoor parts exposed to sun and weather
A suntan is bad for your 3D prints
PLA has relatively poor heat resistance and moderate UV resistance. While it tolerates outdoor use better than some people expect, prolonged sunlight and high temperatures eventually cause problems. Temperatures that it can easily reach over time in direct sunlight, so if you’re printing something that goes outside, or even sits near an open window where unfiltered sunlight shines on it during the day, you’ll want an alternative.
For example, here are some 3D-printed Easter eggs we made to paint and hide in the garden. Likewise, some of my cable organizers would be exposed to sunlight through a nearby window, so PETG was the better choice of material.
It’s, of course, not invulnerable, but holds up better than PLA in sunlight or inclement weather. If you’re going to leave it outside long term, a UV-resistant paint or clear coat can extend its outdoor lifespan. Alternatively, consider ASA.
Functional parts that need to flex instead of snap
Bend it like you know who?
PLA and PETG have very different material properties. PETG has much higher impact resistance. So, if you drop or hit a PETG part, it’s more likely to bend and flex before snapping. PLA is stiffer, making it excellent for rigid parts under static loads, but is brittle and will easily break under a sharp impact.
As such, PETG is an excellent material for functional parts like toolholders, cable clips, drawer latches, camera mounts, battery brackets, replacement appliance clips, and workshop organizers. Just remember that, because PETG is less stiff than PLA, very tight snap-fit designs may require slightly different clearances.
It’s often worth printing the same thing in both PLA and PETG to test which material will perform better for a specific job, especially before you print many copies.
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Parts that will get warm during normal use
Hot to the touch!
The sun isn’t the only source of heat that can affect the materials in your print. There are plenty of places you’d use a 3D-printed object where it could get hot. Common examples that come to mind are mounts, brackets, and enclosures. You could 3D print a computer case, for example, but consider that some of the components in that case can reach high spot temperatures.
Likewise, if you’re going to print enclosures for your SBCs (single-board computers) and stuff them into a hot homelab closet, it’s probably better to have the impact-resistant, moisture-shrugging, material that has a higher temperature point at which it starts to soften.
That said, PETG is certainly not suitable for high temperature applications. It starts to soften and slowly deform at around 80C, but materials like ABS, ASA, polycarbonate, and nylon can handle substantially higher temperatures.
Water-resistant and food-adjacent projects
If it can’t take the heat, get it out of the kitchen
If you’re going to print something that’s liable to get wet or is going to be near food, then PETG is probably the better choice. Some PETG filaments are marketed as food-contact safe, but that comes with some big caveats. Although the base plastic is safe to come into contact with food, additives to that specific filament might not be. Even if the filament is rated as “food safe”, the object you print might have a surface texture that allows for bacterial growth. Likewise, your actual printer may not be a food-safe environment, and contaminants from previous prints or from the printer itself may end up in your print.
So, on the whole, if you’re going to print stuff to use in the kitchen, PETG is the better choice, but you shouldn’t let any of it actually come into contact with your food. So things like clips to keep food in open bags fresh, or hooks to hang utensils should be fine, but don’t print a chopping board or a spoon.
Prints that need to last for years (indoors)
If you’re printing a prototype, decorative figurine, or desk ornament, PLA is usually the right answer. It’s easier to print, produces excellent surface quality, and rarely requires much tuning.
But if you’re making a part that you need to last and maintain its mechanical properties, like replacement appliance parts, workshop organizers, storage brackets, wall mounts, cable management hardware, or household fixtures then you probably want to use PETG.
In the early days, I remember that PETG could be a pain to work with, but even entry-level 3D printers can handle it, slicer software comes with perfectly good presets for it, and the actual filament you can buy has also improved. The post-print finishing process is a little different than ABS or PLA, but don’t be afraid to try printing in PETG if you’ve never done it before.
