Paid

Cavity (Genform)

Turn any STL into printable rigid or silicone mold pieces with sprues and vents; Genform account and plan

Cavity (Genform) is a paid browser tool for casting copies of your own models without CAD. Genform plan required: Starter $29 a month or Business $49 a month ($19 and $39 for the first 12 months when you subscribe by Nov 12, 2026); free 7-day Starter trial for verified new accounts, no card. Exports STL. Last checked 13 October 2026.

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At a glance

Price: Genform plan required: Starter $29 a month or Business $49 a month ($19 and $39 for the first 12 months when you subscribe by Nov 12, 2026); free 7-day Starter trial for verified new accounts, no card
Runs on: Browser
Exports: STL
Multicolor: No, single color
Account: Required to download
Open source: No
Skill level: Easy: a few settings to tune
Best for: Casting copies of your own models without CAD
Selling prints: On a paid plan Confirmed by Genform by email on 13 October 2026: the Business plan ($49 a month) includes commercial use of every tool, Cavity included, while the license is active; Starter is for personal use. The generated STL files themselves may never be sold or shared.
How we checked: Read the tool page and docs Read the Cavity page and FAQ (rigid or silicone molds, demoldability heatmap, sprue and vents, ZIP of binary STLs) and Genform pricing and license terms; Open Cavity Studio redirects to the Genform sign-in page
Checked by: Mike Janssen
Last checked: 13 October 2026

Open generator

Sources: Cavity, Genform plans and pricing, Genform software license terms (checked 13 October 2026)

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What is Cavity (Genform)?

Cavity is a browser-based mold generator from Genform, the company behind PlakHaus and LumHaus. You upload an STL of the object you want to cast, and Cavity repairs common mesh problems, looks for a pull direction and a split that will release from the mold, and builds the mold pieces around it. A heatmap shows where undercuts or trapped areas would stop the part from coming out.

You can choose a rigid mold split into several printed blocks, or a flexible silicone mold held by a printed supporting shell for shapes with deeper undercuts. Before export you set the joints, fasteners, handles, a sprue and vents for the casting material and air. The pieces download as separate binary STL files in a ZIP. Genform says the geometry runs on your device, so the uploaded STL is not sent away for processing.

The studio needs a Genform account: opening it sends you to the sign-in page. Every Genform plan includes Cavity: Starter is $29 a month and Business $49 a month, with a launch price of $19 and $39 for the first 12 months if you subscribe by November 12, 2026, and verified new accounts get a free 7-day Starter trial without a card. Genform confirmed that the Business plan covers commercial use of Cavity, so casts may be sold on that plan. It suits makers who cast resin, plaster, wax or soap copies of their own models and want the mold without CAD.