Bio ball, but cube. Aquarium filtration.

thingiverse

The bio "ball" for aquarium filters is actually a cube with rounded edges. What matters most isn't the shape itself, but rather the large surface area and open structure of the bio balls. The gyroid infill pattern used in these balls can likely be improved upon compared to injection-molded bio balls. This is partly due to the structured surface resulting from layer lines. The downloadable file available does not include a gyroid pattern; instead, it's a plain cube design. If you attempt to use a gyroid-patterned STL with Cura, you'll find that it cannot slice the model into thin walls or print it easily. This particular cube, measuring 30mm on each side, takes approximately 17 minutes to print on my Ender 3 Pro using settings of 30mm/s, 0.28mm layer height, 0.6mm line width, and an 8% infill percentage. To achieve a more dense pattern, you can simply increase the infill percentage.