3D-Printed Footwear Needs Dual Material and Gyroid

3D-printed footwear is a process problem, not a cute STL. On August 24, 2026, Hackaday walked through a home clog workflow: TPU 90A for the shoe, PLA for supports, a dual-nozzle or multi-toolhead printer, and about 15% gyroid infill for squish. If you print large TPU parts on a kitchen-table machine, the lesson is support chemistry and dry filament — not a claim that you should stop buying slip-ons.

What's Happening

In Hackaday’s guide recap on 3D printing footwear at home, the object is bigger than a phone case, and a failed print hurts. The shoe itself is TPU 90A, a hardness the write-up treats as a balance between flex and clean support peel. Supports have to come off. That means a second, rigid filament. The practical hardware is a dual-nozzle head or a multi-toolhead printer so TPU and PLA can share one job without a dozen tool changes by hand.

Hackaday pushes back on the guide’s PETG-support option. In other tests, PETG has welded to flex filaments. PLA usually does not want to stick to TPU. Moisture is the other silent failure: wet TPU prints poorly, and a clog-sized part makes that expensive. Once the materials are sorted, infill is the comfort knob. The recap says a gyroid at about 15% gave the right squish, and that changing the pattern was more effective than changing density. After a successful print, isopropyl alcohol is the suggested release if TPU clings to the plate. The piece is honest that printing your own pair may not beat the store on time or cost. It can still be a useful build if you avoid the usual wrecks.

Why 3D-Printed Footwear Matters for Garage Printers

Most people who try a TPU shoe on a stock single-extruder learn the same two facts. Flexible filament drapes. Supports fuse. You then spend an evening with flush cutters inside a clog. Dual material is not a luxury here. It is how you get a cavity you can actually wear. Drying the spool is in the same category as first-layer temperature: skip it and the large print tells on you halfway through.

Gyroid at 15% is a comfort recipe, not an outsole spec. Lab coupons for wear are often printed much denser. If you copy the Hackaday stack, print a small gyroid pad at 15% and at one step higher before you commit 400 grams of TPU to a pair. Keep PLA as the support unless you have already proven a specific PETG–TPU pairing. And do not treat a printed clog as PPE or as a substitute for a last that has to stay dimensionally true. The shoe can be soft. The jig that holds it, or the clamp you print to finish the sole, is a different job.

How 3D-Printed Footwear Compares to Other Home Options

Approach	What you actually print	Main trade-off
Single-nozzle TPU shoe	One flexible body, same-material supports	Supports weld; cleanup can wreck the clog
TPU 90A + PLA supports (Hackaday)	Dual-material job, ~15% gyroid infill	Needs a dual-nozzle or multi-toolhead printer; dry TPU
TPU + PETG supports	Same idea, different rigid filament	PETG often sticks to flex; only trust a proven pair
Dense gyroid outsole coupons (lab)	30–70% infill in TPU, eTPU, or PEBA	Wear data, not a 15% comfort clog
Continuous-fiber last or finishing jig	Does not make the shoe; holds shape while you trim	Different machine and process from TPU 90A

What the Research Says

Li, Jung, Lang, and Lee printed gyroid cubes for footwear materials on a material-extrusion machine: foamed eTPU, standard TPU, and PEBA, at 30%, 40%, 50%, and 70% infill, 220 °C, 50 mm/s. PEBA held the gyroid geometry most cleanly. At 70% density it also posted the lowest wear rate in the set, 0.33%. That is an outsole-oriented coupon study, not a 15% clog. It still backs Hackaday’s instinct that gyroid density is a material setting, not decoration (Li et al., 2026). Do not read 0.33% as a TPU 90A number. It is PEBA at high fill.

Printed TPU outsoles already have FDM data. Chen and Lee built lightweight TPU star-pattern outsoles with 3-, 4-, and 6-pointed stars at 5, 7.5, and 10 mm thickness. As thickness rose, they saw denser fusion and fewer microvoids. One 10 mm, 3-pointed prototype (LW 3-PS-10) came in at 0.706 specific gravity, 68.3 g, and 127 mm³ DIN abrasion, with a large plantar contact area in their pressure maps (Chen and Lee, 2022). Together the two papers say: pattern and density change how a TPU sole feels and wears. A garage clog at 15% gyroid is in that family. It is not the same coupon as a 70% PEBA outsole or a 10 mm star sole.

Frequently Asked Questions

Can I make 3D-printed footwear on a desktop FDM printer?

You can print a clog-style shoe in TPU 90A if the machine can run a second rigid material for supports. Hackaday’s guide uses PLA supports on a dual-nozzle or multi-toolhead printer, dry TPU, and about 15% gyroid infill for flex. A single-nozzle machine will fight the support peel. A failed full-size print still costs a lot of time and filament.

What infill should I use for 3D-printed TPU shoes?

Hackaday reports gyroid at about 15% infill gave the clog the right squish, with pattern mattering more than density. Lab outsole gyroids are often denser. Li and colleagues tested 30% to 70% cubes in TPU, eTPU, and PEBA. Treat 15% as a starting point and print a coupon first.

Is PETG or PLA better as support for TPU footwear?

The clog guide allows PETG, but Hackaday prefers PLA. PETG often welds to flexible filaments; PLA tends to stick to itself and release from TPU. Dry the TPU spool. If the shoe sticks to the build plate after a good print, isopropyl alcohol is the release they suggest. Dual material is still the requirement, not a clever single-nozzle trick.

Fibricate's Place in This Story

A TPU clog and a stiff last are easy to mash together because both sit on a foot. They are not the same print. Companies like Fibricate, whose FibreSeeker 3 continuous carbon fiber 3D printer co-extrudes polymer with a continuous tow from feedstock such as the continuous carbon fiber spool, are not selling a TPU 90A shoe profile. Print the flexible body when the job is squish and peel. Reach for directional fiber when you need a finishing jig, a lasting form, or a clamp that should not rely on 15% gyroid weld lines. One part yields. The other holds still.

What to Watch Next

Watch whether more clog and sandal files ship with explicit dual-material support bodies instead of “print in TPU and hope,” and whether filament makers publish TPU–PLA peel data next to temperature. Also watch gyroid libraries that split a sole into a 15% comfort core and a denser contact patch, the way lab outsole coupons already vary fill. Over the next year, expect more home TPU footwear, plus the usual reminder that a wet spool will still ruin a six-hour clog. The interesting split is who treats a shoe as one flex body and who treats supports, infill, and the finishing jig as three materials. Both can live on the same bench. They are not the same job.

References & Further Reading

1. Li, J., Jung, I., Lang, C., & Lee, S. (2026). Effects of gyroid lattice relative density on wear and mechanical performance of 3D printed TPU and flexible nylon for footwear. iScience.
2. Chen, X., & Lee, S. (2022). Physical Property of 3D-Printed N-Pointed Star-Shaped Outsole Prepared by FDM 3D Printer Using the Lightweight TPU. Polymers.
3. Straight Talk On 3D Printing Footwear At Home. Hackaday. Retrieved August 26, 2026.