Why We Print in ASA

Why We Print in ASA (Even Though It's Harder and Costs More)

Most 3D-printed products you'll find for your car are made from whatever prints easily. We made a different choice, and it costs us more time and more money on every part. Here's why we print in ASA anyway, and why it matters for something that's going to live inside a vehicle.

Your Car Is a Torture Test for Plastic

A parked car in summer is one of the harshest environments a small plastic part will ever face. Interior temperatures can climb way above the outside air temp, and everything on the dash or in the windows takes direct, sustained UV. A part that's fine on your desk can warp, sag, go brittle, or fade after a few hot afternoons in a car. So the real question isn't "will this print look good," it's "will it still work after a summer of abuse." That question is what drove us to ASA.

What Makes ASA the Right Material

ASA was essentially developed to be a weather-resistant engineering plastic. Two properties matter most for car interiors:

• Heat resistance. ASA holds its shape and strength at the elevated temperatures a closed cabin reaches in direct sun, well beyond where easier materials start to soften and deform.
• UV stability. This is ASA's signature strength. It resists yellowing, fading, and the slow embrittlement that sunlight causes in most plastics. A part printed in ASA is built to still look and perform right after seasons of sun exposure, not just weeks.

How It Compares to the Alternatives

It helps to see why the easier, cheaper materials don't make the cut for an in-car part:

• PLA is the most common material in hobby printing because it's cheap and easy. It's also the worst possible choice for a car: it starts softening at temperatures a parked cabin easily exceeds in summer, so a PLA part on your dash can literally droop. We don't use it for products.
• PETG is a real step up, tougher and more heat-tolerant than PLA, and fine for many uses. But it doesn't match ASA's long-term UV stability, and under sustained sun it can degrade faster. It's acceptable; it isn't the best tool for this job.
• ABS is close to ASA in strength and heat resistance, which makes sense, ASA is chemically related to it. The difference is sunlight: ABS yellows and grows brittle under UV. ASA was created specifically to fix that weakness, which is exactly why we prefer it for parts that see the sun.
• ASA brings the heat resistance, the UV stability, and the durability together in one material. For a part that lives in a sun-baked cabin, nothing else in this class does the whole job as well.

The Catch: ASA Is a Pain to Print

If ASA is so good, why doesn't everyone use it? Because it's genuinely difficult to print well. It's prone to warping and cracking if the temperature around the print isn't carefully controlled, which means it really wants an enclosed, heat-managed printer rather than an open hobby machine. It's less forgiving than PLA or PETG, and dialing in a clean, strong, dimensionally accurate part takes experience and a fair number of failed attempts along the way. It also costs more per roll than the easy materials.

ASA adds another complication most easy materials don't: it off-gasses while it prints. Heating the plastic releases fumes and fine particles, so printing it responsibly means an enclosed printer and proper ventilation, not just running it on a desk in the corner. That's more equipment, more setup, and more care on our end for every print. It's one more reason a lot of shops reach for something easier, and one more piece of difficulty we've chosen to take on so the finished part can be the right material for the job. Once a part is printed and cured, it's stable, the handling that ASA demands is a production concern we manage in the shop, not something that follows the part into your car.

We've taken on all of this on purpose. We tuned our process around ASA, print on equipment built to handle it, ventilate for it, and eat the higher cost and occasional failed print, because the alternative is selling you a part that fails the first time your car gets hot. We'd rather do the hard thing once than hand you something that doesn't last.

What About Injection Molding? Let's Be Honest.

If you've priced Rivian accessories, you've seen injection-molded parts, and it's fair to ask why ours are 3D printed instead. We're not going to pretend 3D printing wins on every measure. It doesn't, and here's the straight version.

Injection molding forces molten plastic into a steel mold under high pressure, producing a single homogeneous part with a smooth factory finish. A 3D-printed part is built up layer by layer, and that's its real weakness: the bond between layers can be a bit weaker than the solid body of a molded part, especially along the print's vertical axis. A molded part also has that seamless injection-molded surface out of the box. On raw per-part consistency and finish at massive scale, molding has genuine advantages, and we'd be lying if we said otherwise.

But here's why molding is the wrong tool for what we do. Injection molding only makes economic sense at huge volumes, because every part requires a custom steel mold that costs many thousands of dollars to cut before you make a single unit. That upfront tooling cost has real consequences for you:

• It kills iteration. Once a mold is cut, the design is frozen. Improving it means paying for a whole new mold, so molded products tend to ship once and never change. Our designs get revised continuously based on owner feedback, because changing a 3D-printed part costs nothing but a file update. The part you get reflects every improvement to date, not a design locked in stone years ago.
• It rules out low-volume and niche parts entirely. A lot of what we make serves a specific configuration or a smaller slice of owners. Those parts would never justify a five-figure mold, which is exactly why nobody mass-produces them. 3D printing is what makes a community-driven catalog of specialized parts possible at all.
• It doesn't fit an open-source, print-it-yourself model. You can download our files and print our parts at home. You cannot injection-mold them in your garage. The whole point of what we do only works because these are printed designs.

And the layer-strength concern? For a headrest mount, a cup holder, or a phone bracket, it's a non-issue in practice. We design with print orientation and wall thickness chosen for strength, and ASA printed properly is plenty strong for the loads these parts actually see. Injection molding solves a problem, mass-producing millions of identical units cheaply, that we don't have and don't want. What we want is to make well-designed, continuously-improved, sun-proof parts for a community, in the exact quantities that community needs. For that, 3D printing isn't the compromise. It's the right answer.

What This Means for You

When you install one of our parts, you're getting something chosen and built to survive the actual conditions inside a vehicle: the heat, the sun, the years. That's the entire reason we accept a harder, pricier material instead of the convenient one. The difficulty is ours to deal with. The durability is yours to keep.