Free Multicolor No account needed

Iteration3D

Type your sizes to get tube adapters, O-rings, brackets, boxes and organizers as STL

Iteration3D is a free browser tool for exact-size replacement and workshop parts. Free downloads with no account or email, after ticking a terms box. Every model checked was marked Free; the license varies by template (CC0, CC BY, CC BY-NC-ND or the site's own non-commercial ITE IPU v1.0). Exports STL. Last checked 26 September 2026.

Open Iteration3D See alternatives

Opens iteration3d.fr

At a glance

Price: Free downloads with no account or email, after ticking a terms box. Every model checked was marked Free; the license varies by template (CC0, CC BY, CC BY-NC-ND or the site's own non-commercial ITE IPU v1.0)
Runs on: Browser
Exports: STL
Multicolor: Yes
Account: Not needed
Open source: No
Skill level: Beginner: fill in a form
Best for: Exact-size replacement and workshop parts
Selling prints: Depends on each model's license Each model page names its license, and it follows the template. O-rings, washers, tubes and blocks are CC0; compartment boxes, round boxes, enclosures, inline tube adapters, pots and handles are CC BY, so prints can be sold with credit. The round vent is CC BY-NC-ND, and the box with lid, L-bracket, pipe elbow, pipe clip, organizer, honeycomb grid, splitter and duct adapters use ITE IPU v1.0, which bans selling or sharing prints and files.
How we checked: Opened the generator Box with lid form loads without an account or bot check: length, width and height 20 to 300 mm, wall 2 to 6 mm, and the page offers an on-demand build when a size is missing
Last checked: 26 September 2026

Open generator

Sources: Box with lid template, Licenses, FAQ: what the download includes (checked 26 September 2026)

Something out of date? Let us know

Made Iteration3D? Get the listing badge

What is Iteration3D?

Iteration3D is a free browser tool that turns typed measurements into printable technical parts. It has 22 templates for adapters and airflow, storage, and hardware. You pick one and type a few values, such as inner diameter and cross section for an O-ring. The site first searches its library of more than 11,000 models that earlier visitors generated. If your size is missing, 20 of the templates offer to build it: you check a summary of your values, start the job and wait for a progress bar, and the new model joins the public library.

The range covers tube and duct adapters, pipe elbows, splitters, honeycomb fan guards, vent grills, L-brackets, pipe clips, washers, handles, pots, drawer organizers, compartment boxes and screw-lid enclosures. A compartment box with colored row rings and a honeycomb grid with a second-color border come as separate STL parts for multicolor printing. Each download is a ZIP with the STL files, a list of the values used and a license file.

Downloads are free and need no account. The license is set per template: O-rings, washers and tubes are public domain, several box and adapter templates allow commercial use with credit, and about half, including the box with lid, are personal and non-commercial only. It suits makers who need a part in an exact size.

What you can make

Tube adapters, duct transitions and multi-way splitters
O-rings, washers and flat gaskets
L-brackets, pipe clips and U-shaped handles
Boxes with lids and screw-lid enclosures
Drawer organizers and compartment boxes
Honeycomb fan guards and round vent grills

How to use Iteration3D

Open Iteration3D and pick a template such as O-ring, box with lid or tube adapter
Type your dimensions into the template's search form
Download a matching model, or click Request build if that size does not exist yet
Check the summary of values, start the build and wait for the progress bar
Tick the terms box, download the free ZIP and slice the STL files

What you'll need to print it

Filament and parts that suit what you make with Iteration3D.

PETG

TPU (flexible)

Bambu Lab TPU 95A HF (affiliate link) Amazon
Overture TPU 95A (affiliate link) Overture

Multicolor PLA

Also handy

Filament dryers and dry boxes

SUNLU FilaDryer S4 (affiliate link) Amazon
Polymaker PolyDryer (affiliate link) Amazon

Some of these are affiliate links: we may earn a small commission, at no extra cost to you. More about that

Iteration3D pros

More than 11,000 ready-made sizes in the library, so a common part often downloads straight away
Covers workshop parts few generators offer, such as O-rings, duct adapters, pipe elbows and pipe clips
The search form shows the allowed range for each value, and the ZIP includes a file listing the exact values used

Iteration3D cons

About half the templates, including box with lid, L-bracket, pipe elbow and the duct adapters, carry a personal, non-commercial license, so check the license on each model before selling prints
New sizes are built in a server queue, so you wait for a progress bar instead of watching a live preview while you type
The site says it is not designed for phones, and every model seen downloads as STL only