3D Printed Slime Ball

Lisa Ernst · 16.11.2025 · Technology · 8 min

This article provides a compact guide to 3D printing Ruven Bals' Slime Ball, from obtaining the file to the finished fidget object. It is based on the designer's and community's experiences and highlights the specifics of this print-in-place model.

Quelle: Own Representation

Introduction

The Slime Ball by Ruven Bals is a fidget object that, despite being made of hard plastic, feels almost like liquid. It is described as a "variation of the Twisty Grid“ " and is constructed to slide through your fingers like a viscous liquid, even though it is created via FDM-3D-Druck aus PLA . This guide shows how to print this model from file to functioning fidget ball, including specific settings, links, and pitfalls, based on experiences from Kady 3D Printing.

The Slime Ball is a Print-in-Place-Fidget-Ball: Numerous thin struts and joints are nested within each other so that the ball feels soft and "slimy" when squeezed and pulled, even though it is made of a hard thermoplastic like PLA. Print in Place means that all joints are created in a single printing process and can move freely after removing the support structures, without needing to assemble parts.

It is typically printed with an FDM or FFF printer, which melts a plastic filament and deposits it layer by layer to form a three-dimensional shape. Common devices include the Bambu Lab X1-Carbon, Prusa i3, or Anycubic Kobra; Kady 3D Printing shows the ball, for example, on a Bambu Lab X1-Carbon with eSun PLA+. The designer himself describes a similar model, the Squish-Ball, , as a bundle of scissor linkages that form a metamaterial; the Slime Ball uses the same metamaterial approach, just in a closed spherical form. The unique feel therefore comes not from soft rubber, but from the geometry and play within the structure.

Analysis & Facts

Ruven Bals' specific Slime Ball model is available on Thangs , but requires a membership for direct download due to licensing restrictions. The designer explains that the ball is a variation of his Twisty Grid design and is intended to feel "like liquid flowing through your hands."

Quelle: etsy.com

Diverse 3D printed slime figures demonstrate the creative possibilities of 3D printing.

The page lists specific printing data: Material PLA, layer height 0.2 mm, infill 10 percent, manual supports, and no brim specified, plus about 110 grams of filament and around eight hours of printing time on a Bambu A1 for a complete ball. Ruven Bals points out that he has created an "Easy to print" version without supports, which, however, does not result in a closed sphere and primarily serves to test filament behavior. Kady 3D Printing it is clearly stated that this is not a beginner's print: it is suggested to print the simpler version first, use standard PLA settings, but reduce the complete profile to about 50 percent speed, and for the fully closed sphere, either use the presupported files prepared by the designer or specifically supplement the automatic supports.

Kady 3D Printing reports a successful print on a Bambu Lab X1-Carbon with eSun PLA+, without additional rafts and with 15 percent infill, explicitly recommending the use of the presupported file and printing at a slow speed. General guides to PLA confirm that 0.2 mm layer height, 10 to 15 percent infill, and moderate speeds are sensible standards for decorative and fidget parts.

The goals behind this design are clear: the ball is intended to combine mechanics and haptics, thus demonstrating a challenging print-in-place metamaterial on the one hand and providing a fidget object that you'll hardly want to put down on the other. For

For users, the ball plays a dual role: it is a fidget to knead in everyday life and at the same time a sensitive test for print quality, filament choice, and slicer settings, because small errors in overhangs, supports, or layer adhesion immediately become visible as rough spots or blocked segments. Ruven Bals , the Slime Ball is part of a portfolio of fidget toys, grid structures, and kinetic objects offered as digital products on Thangs.

Quelle: yankodesign.com

3D printed stress balls with a honeycomb-like grid pattern as an example of tactile 'Slime Ball' objects.

For users, the ball plays a dual role: it is a fidget to knead in everyday life and at the same time a sensitive test for print quality, filament choice, and slicer settings, because small errors in overhangs, supports, or layer adhesion immediately become visible as rough spots or blocked segments.

In this Video , the designer himself explains why the ball is difficult to print, which version is suitable as a test, and how to proceed with removing supports without destroying the grid.

The core data are well documented: the Slime Ball comes from Ruven Bals, is a variation of the Twisty Grid, is described on Thangs with PLA, 0.2 mm layer thickness, 10 percent infill, manually placed supports, and a print time of about eight hours for around 110 grams of filament. The recommendations to use the presupported files, not to activate additional automatic supports, and to reduce the print speed to about 50 percent of the standard profile are also well documented.

It remains unclear whether the ball functions equally reliably with every printer-filament combination; the designer points out that filaments behave differently and that the community should collect working filaments in the comments. User experiences show that some users print the ball perfectly on the first try, while others complain about separating supports, stuck segments, or brittle silk filaments.

It would be misleading to assume that this is a robust rubber toy for children: most prints use hard PLA, and FDM parts are considered more prone to breakage and chipping than injection-molded plastic balls due to their layer structure. Manufacturer blogs on 3D printed fidget toys therefore remind users to check printed parts for sharp edges and loose small parts before giving them to children.

Practical Implementation

In the community, positive voices prevail for this model: On Thangs , users praise the design as "on another level" and report very "slimy"-looking behavior, especially with dual-color PLA, which creates visually striking grid structures. Kady 3D Printing shows in photos and Video, how a Slime Ball made of eSun Dual-Color-PLA on a Bambu Lab X1-Carbon is created and describes the result as particularly pleasant to knead.

Quelle: amazon.com

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At the same time, there are skeptical voices that see the ball more as a stress test for their own printer: in comments, users report failed prints, supports that adhere too strongly, and rough spots that had to be improved through slight parameter changes such as lower speed, different support settings, or drier filament. Discussions about print-in-place fidget toys on Reddit also show that while such models are popular with people with ADHD, they have very different individual effects on concentration and restlessness.

If you want to print your own copy, you can orient yourself step-by-step based on existing experiences.

First, you need the model: download the Slime Ball from Ruven Bals auf Thangs , observe the license terms, and for a start, choose the "Easy to print" version to test filament and printer. Alternatively, you can find other slime or squish balls via search portals like Yeggi if you want to start without a membership.

Second, set up your slicer: take PLA with about 0.2 mm layer height, 10 to 15 percent infill, three outer walls, and standard speed as a base, then reduce the print speed to about 50 percent, and let the fans run cleanly from the second layer onwards. For the presupported file, deactivate additional supports; for the unsupported file, activate them, as described by the designer.

Third, start the print and observe the first layers particularly closely: if the ball adheres cleanly to the bed, the support structures are stable and do not form wild spaghetti, you can let the print run relatively relaxed, even if eight hours of running time for a complete ball is normal.

Fourth, post-processing follows: after cooling, carefully remove the ball from the plate, break off brim remnants, remove the supports with a fine screwdriver or needle-nose pliers, and play the joints free step-by-step until all segments can move against each other. If some segments still stick, careful bending back and forth helps; however, too brutal force can break fine struts.

Fifth, critically examine the result: if there are sharp edges, torn struts, or loose particles, you should rework them or, if in doubt, reprint the part before children play with it. For safer everyday use, it is advisable to test more robust filaments and slightly increased wall thicknesses, even if this makes the ball a little stiffer.

This Kurzclip by Kady 3D Printing shows how the finished ball looks in hand and how much the appearance and "slime" feel depend on filament color and clean layers.

Results & Outlook

It remains open how durable such metamaterial balls are under continuous load, as there is currently little systematic data on the fatigue of FDM grids in this form, although studies generally point to the reduced strength of layered objects. It is also unclear how much micro-abrasion occurs with intensively used fidget toys and what role this plays for indoor air and the environment, as corresponding research on printed toys is still rare. Finally, the economic development between free and paid models in the fidget design sector is still in flux, as platforms like Thangs continue to experiment with subscription models, bundles, and print-on-demand offers.

For you, this means: the Slime Ball is not a quick, side-project print, but a deliberately chosen project with which you can deepen both your printer calibration and your understanding of print-in-place geometries. If you adhere to the documented settings, patiently experiment with speed, filament, and supports, and critically examine the result, you will get a fidget ball that mechanically and visually goes far beyond simple test objects. And precisely therein lies the appeal: you learn with a concrete, haptically exciting object what is possible with FDM-3D-Druck today – and where the limits of material, geometry, and practice lie.