Free planter mold maker
Design a printable mold for casting concrete, cement or Jesmonite planters and pots in your browser, preview it in 3D, and download a print-ready STL or 3MF in seconds. Outer formwork plus an inner core for a clean hollow cavity - no account, no software to install.
Free · runs entirely in your browser · STL & 3MF download
How it works
- Pick a pot or planter profile, or upload your own shape - cylinders, tapers, bowls and faceted pots all work.
- Set the outside size and wall thickness in true millimetres; the generator builds outer formwork plus an inner core so the cast comes out hollow.
- Preview on a virtual print bed, download the STL or 3MF, then cast your concrete, cement or Jesmonite in the gap between the walls.
What you get
A print-ready formwork set sized in real millimetres: an outer mold and a matching inner core that together leave a clean-walled hollow planter. The generator prints the pieces to cast a flexible silicone mold, so you can pour planter after planter and demold without cracking the concrete. Everything is generated on your device - your model never leaves the browser.
Materials & casting tips
- Mix: a fine sand-free concrete, cement-all or Jesmonite gives smooth walls and captures printed detail. Tap or vibrate the mold to release trapped air.
- Drainage: add a small dowel or bolt in the base of the core to leave a drainage hole, or drill one after the piece cures.
- Release: a silicone mold releases concrete cleanly; if casting against a printed mold directly, use a spray release and a little draft.
- Sealing: seal finished concrete planters with a masonry sealer if you plan to plant directly in them, to protect roots and prevent efflorescence.
- Filament: PETG holds up best to repeated wet casts; PLA is fine for the printed masters you cast silicone from.
Who it's for
Makers casting concrete and Jesmonite planters, pots and vases to sell or gift, who want a custom shape without CAD. If you would rather print a planter directly in plastic instead of casting one in concrete, use the STL to planter tool. For solid pieces like coasters and trays, see the concrete mold maker.
FAQ
Is the planter mold maker free?
Yes. Designing and downloading a planter mold is free and runs entirely in your browser - there is no server render and no account required to start.
How do I get a hollow planter, not a solid block?
The generator builds an inner core as well as the outer formwork. Concrete fills the gap between them, so the cast comes out hollow with an even wall. You set the wall thickness in millimetres.
Can I add a drainage hole?
Yes. Set a small dowel or bolt into the base of the core before pouring to leave a drainage hole, or drill one with a masonry bit once the planter has cured.
What file format do I get?
A standard STL or 3MF that loads straight into any slicer - Cura, PrusaSlicer, OrcaSlicer and others.
Is this the same as the STL to planter tool?
No. This makes a mold to cast a planter in concrete or Jesmonite. The STL to planter tool turns a model into a planter you print directly in plastic.