Resin-based printing methods (stereolithography, SLA; digital light processing, DLP; liquid crystal display, LCD) are the obvious first choice for transparent parts since the layer lines are less apparent than filament-based methods. These deliver near-clear results without much post processing.

Transparent resins, when cured in UV light, create clear parts, but there are some tips to getting the clearest prints, such as printing at 100% infill density. This trick will definitely add hours to your print time, but it produces parts that can be crystal clear, even functional camera lenses.

Micro resin 3D printing technologies that produce tiny, finely detailed objects for research or medical applications can also achieve transparency. Microstereolithography (µSLA) prints parts on the micro-scale, or resolutions between 2 microns (µm) and 50 microns. It requires specialized resins, sophisticated lasers, and the addition of focusing lenses, which generate almost unbelievably small points of light. Two-Photon Polymerization (TPP) is a similar technology to µSLA but gets even smaller. TPP is currently used in research, medical applications, and manufacturing for tiny parts, such as micro-sized electrodes and optical sensors.

Cutting Edge

3D Printing Clear Dental Aligners

There’s another resin-based technology from ceramic 3D printing company Lithoz, in partnership with German glass manufacturer Glassomer. Called “LithaGlass,” the product begins with a quartz-glass-based slurry enabling the flexibility of 3D printing and the performance of fused silica glass. The post-processing involves the sintering of the print in an oven that reaches 1,300°C to melt away the polymer binder and fuse the glass particles into a solid, transparent piece. Despite the melting away of material, the company claims that the parts retain their shape after an isotropic (equal in all directions) shrinkage. As of 2024, this material is still classified as a “pre-series material” research project on the Lithoz website.

Material Jetting is another resin-based method where UV-curable resin is deposited drop by drop onto a surface and cured instantly with UV light. Polyjet is the material jetting method developed by 3D printer maker Stratasys. To get clear prints using Polyjet, you begin with a clear resin (such as VeroClear by Stratasys). For best results, Polyjet parts must typically be finished with a lacquer, polish, or photobleaching process.

3D printer maker Mimaki’s proprietary technology is also a type of material jetting. It uses inkjet print technology to deposit UV-curable liquid resin in white, clear, and CMYK, along with soluble support material on a bed layer by layer. Each layer is cured by the UV light.

Fused deposition modeling (FDM) enables you to achieve transparent parts with transparent filament as the starting material. This process leaves visible ridges on the edges of finished parts, but with post-processing and some tips we detail below, they can be almost completely removed.

You’re not limited to one type of clear plastic. Clear can be achieved with PLA, PETG, Polypropylene, and several other polymers ranging from economical and decorative to industrial and biocompatible.

If you’re looking to print a large item, such as a lamp of signage, clear material in pellet form — used with pellet-material extrusion systems — is more economical. Often the same material used in injection molding, clear pellets are available in more variety than their filament cousins but often not sold in small quantities.

Glass extrusion 3D printing is up-and-coming but mostly relegated to science labs and artist studios considering the industrial equipment and temperatures. It’s not widely commercially available. Read more in our article on glass 3D printing linked below.

A New Take on Glass

Glass 3D Printing: All You Need to Know

With resin transparent 3D printing, best practices for achieving true transparency happen mainly in post-processing, which we cover below, but one tip to try during printing is adding a bit of blue dye to clear resin in order to counteract the yellowing process of the UV light during the curing – though that can result in cloudy prints and some experimentation is required.

When printing using material extrusion, or FDM, there are certain print settings that can improve print quality. For example, you should use a higher hot end temperature, a larger layer height, and a low infill. These steps will ensure that the clear material is properly melted, spaced out, and hollow enough for optimal transparency.

Also consider your part orientation. Do you need transparency perpendicular to the Z-axis, in the XY-plane, or complete transparency? For making a transparent vase, you most likely will only need transparency in the X- and Y-axes (across it). For making a flat window, you only need transparency through the Z-axis. For complete transparency, you’ll need transparency in all axes.

Achieving transparency in the X- and Y-axes requires large layer heights relative to the nozzle size used. Larger, more spherical layers tend to refract less light, thus leading to a more see-through 3D printed part. According to material manufacturer Taulman3D, printing at 70% – 90% of the nozzle diameter results in more transparent prints.

Best FDM Print Settings to Improve Transparency:

• Print slower (25% – 30% of your normal print speed)
• Print thicker layers by using a larger nozzle
• Print at 70% – 90% of the nozzle diameter to obtain a structure that refracts less light
• Use the highest nozzle temperature within the filament’s range (ensuring fusing of the plastic)
• Use a flow rate above 100% (such as 108%)
• A single direction for infill
• Disable your fan or print cooling

With most 3D printing, post-processing is necessary to achieve the desired results. Transparent printing is no different. In fact, much of the actual transparency is achieved here.

Although resin can produce truly stunning transparent parts right from the printer once you put those parts through the standard resin washing and curing you often end up with cloudy opaque parts. Don’t worry, you can get them back to a transparent finish with some post-processing.

First, resin parts must be cleaned or any resin residue. Typically this is done with isopropyl alcohol. Then they are cured under UV light. Avoid over curing to prevent yellowing. Finally, parts must be sanded, polished, and finished with a clear coat or lacquer.

For best results, sanding should begin at 400 grit, moving incrementally all the way to 12,000 grit, at which point parts become reflective. After sanding and polishing, spraying on a clear coat produces a nice finish and also protects from UV exposure which can lead to yellowing. Parts can alternatively be dipped in resin for a truly smooth finish (though this is not ideal for lenses).

Post-Processing Techniques

Post Processing: Crystal Clear & Rubber Soft 3D Prints

An industrial post-processing method used with PolyJet 3D printing is known as photobleaching. This method requires an additional machine, such as the ProBleacher made by Stratasys.

When it comes to FDM prints, sanding off the layer lines as described above in the resin section is required.

After you’ve spent some time removing surface material from your 3D printed parts, it’s time to add material. Clear coating is often overlooked but remains a simple, effective, and quick way to smooth, fill imperfections and enhance the clarity of clear parts.

Clear coats and lacquers come in different finishes from matte, satin to semi-gloss, and gloss. Although there are coatings for 3D printed parts, lacquers for clear automotive parts work just as well.

Spray the lacquer from around 30-cm away, moving side to side while spraying to ensure a consistent coat and to avoid overspray. Depending on the specific spray you may want to wait at least 24 hours at room temperature before handling the part.

Once dry, sand again with a very high grit sandpaper (1000+) to remove any imperfections in the coat, such as stray dust particles, overspray, or “orange peeling”. Once sanded, rinse the part in clean water and ensure the part is dry and free from dust before applying another coat.

Depending on how coarse and rough the surface is, you may need to apply additional coats of lacquer. A word of caution though, do not be tempted to apply a thick, heavy coat of lacquer because this will result in a tacky surface that never seems to dry.

Some filament-based 3D printed parts can be treated with solvents, but be warned that solvents cannot be used on all FDM print materials. Using a solvent on ABS parts, for example, results in an unpleasant cloudy finish.

PolySmooth filament, for example, is designed specifically for models which are intended to be transparent. PolySmooth can be finished with ethanol, which is sprayed onto the print and left to dry for several days. Several reapplications turn the part transparent. However, the part may lose dimensional stability as a result of the solvent.

There is an ever-growing number of resins for SLA and Polyjet printers. These can be found in a range of price points, from consumer-friendly options like Siraya Tech Simple Resin Clear to dental or medical-grade products like Nexa3D NXE xMed 412 Clear Resin.

When selecting a clear resin always check to see which one is approved for use in your 3D printer. In other words, which one has a printer profile, which means that the printer manufacturer has tested this resin in that particular machine and developed the optimal print settings for it. You’re not limited to printer-approved materials but if you select a third-party resin, you’ll need to do some testing to come up with your own optimal workflow.

Biocompatible Resins

Specialty Resins

As we mentioned above, filament materials for 3D printing various plastics, from PLA and PETG to ABS and polycarbonate. Among these, PLA and ABS are the most commonly used, with PLA being one of the easiest to work with and yielding excellent transparency. If you have other mechanical requirements for you parts, such as withstanding outdoor conditions, you’d want to go with PETG or polycarbonate.

We have a full guide to the best clear filaments at “Clear Winners: The Best Transparent & Clear PLA Filaments of 2023.”

Clear Winners

The Best Transparent & Clear PLA Filaments

If you’d like to get something printed in transparent filament but don’t want to deal with any printing challenges, try Craftcloud by All3DP. When professionally printed, some of the material options come out looking almost exactly the same as glass.

If your product prototype or end-use part has to be transparent and you don’t have the time or inclination for the labor involved in the process, the easiest option is to put your product in the hands of professionals.

3D printing services will almost always use industrial-grade 3D printers, just as PolyJet, and higher-quality resins than those available for home use.

When ordering online and faced with choosing clear FDM or clear resin (SLA or PolyJet), FDM will be cheaper but resin will be more clear, generally. Size may be a constraint for resin unless you find a service with one of the very large 3D Systems resin machines.

For companies that offer a transparent material options the post-processing steps that are required for transparency are already included but for some company, you may need to select a “finish.” In this case, chose polished or smoothed.