Since PVB filament is not an option due to its insufficient strength for my needs, I’ve started testing with PETG instead.

If you search on Printables, you’ll quickly come across an article by user “Rygar1432” about printing glass-like parts. In my opinion, it’s a solid starting point—although I don’t fully agree with all of his arguments.

According to “Rygar1432”, the three most important factors are:

• A printing speed of 20 mm/s
• No top or bottom layers, combined with unidirectional infill
• A layer height of 0.1 mm using a 0.4 mm nozzle

I completely agree with the first two points:

1) Print Slowly

You need to print very slowly to avoid any optical distortions in the filament during printing. Since there are many different speed settings for various scenarios, I chose to set a limit using the Maximum Volumetric Speed parameter. This seems to be the only place in Prusa Slicer where a global speed limit can be enforced.

The calculation is: 20 mm/s * nozzle diameter * layer height

For example:

• 0.4 mm nozzle and 0.1 mm layer height → 0.8 mm³/s
• 0.8 mm nozzle and 0.4 mm layer height → 6.4 mm³/s

Additionally, turning off the part cooling fan completely also seems to help. Letting the filament cool slowly minimizes the formation of cloudy areas in the print.

2) Use Unidirectional Infill

The infill strategy is also crucial. Unidirectional infill reduces optical disturbance within the printed layers. I use:

• 100% infill
• Aligned Rectilinear pattern (ensures all infill is printed in a single direction)

3) Nozzle and Layer Height

This is where I disagree with “Rygar1432”. Several other sources suggest that printing with the largest possible nozzle and layer height improves clarity.

The reason: every layer and every individual line of filament introduces optical distortion between layers and paths. Using thicker layers and wider lines minimizes these interfaces and therefore increases transparency.

I performed a comparison between:

• 0.4 mm nozzle, 0.1 mm layer height (as recommended by “Rygar1432”), and
• 0.8 mm nozzle, 0.4 mm layer height

The latter produced significantly better results!

Software & Settings

“Rygar1432” uses Orca Slicer, while I’m using PrusaSlicer, so I had to experiment with its settings, which differ considerably.

He also recommends additional modifications such as increasing infill extrusion width. However, these didn’t work well in my setup—the infill received too much filament—so I’ve ignored those for now but plan to revisit them later.

I’ll attach screenshots of my changes to the “Print Settings” and “Filament Settings” in PrusaSlicer for reference.

Filament Choice

Currently, I’m using Overture PETG Transparent, as suggested by “Rygar1432”. However, I believe Prusament PETG Clear is quite similar and worth testing as well.