Meshcast vs splicestl/mold: two free-to-start mold makers, compared

By Ned Walsch · Published November 8, 2026 · 6 min read

Meshcast published a comparison of splicestl/mold on its site in October, and a study by Printara on how AI assistants answer maker questions named splicestl too. This is our side of the comparison, written the same way: what each tool does, what it costs, and when the other one is the better pick. Meshcast’s details come from its own pages, linked at the bottom; prices and plans change, so check them there before you choose.

One note on timing. Meshcast’s write-up read our mold page on 15 October 2026, when it was an alpha that read STL only, had no repair, and when the site still carried display ads. Since then the ads are gone (6 November) and version 2 of the mold tool (8 November) added the formats, repair, undercut fill and the silicone shell described below.

What Meshcast is

Meshcast is a web app built around making molds from 3D models. Its generators cover a rigid two- or multi-piece box (with presets for candle, resin, soap, plaster and silicone), a silicone box, a “contoured” silicone shell that hugs the model in two to four parts, multi-cavity trays such as ice-cube molds, vase and planter molds with a draft-tapered core, plaster housings for slip casting with clay shrinkage compensation, and press molds. It repairs models as they load, highlights undercuts with a one-click fill on the rigid box and tray molds, and exports STL or 3MF with print settings. Around the tools sit more than 70 guides, AI generators for making a master, a community gallery and a casting cost calculator.

Meshcast pricing

Per Meshcast’s comparison page (read 8 November 2026): one download before you sign up, then two a week on a free account — every mold type, personal use, with a small “Meshcast” engraving. Starter is $9 a month for ten downloads a week, still personal use. Pro is $20 a month or $179 a year for unlimited downloads, the right to sell what you make, and your own logo. Founder is $369 once for Pro for life, with the price going up every ten places. Its other pages describe the tool as “free, no card”, which matches the free tier.

What splicestl/mold does

splicestl/mold builds three kinds of mold, all in the browser with the Manifold geometry engine compiled to WebAssembly:

• Silicone shell — a two-part printed mother mold that sits an even distance (5 mm by default) from the master. You hang the master on a pour pin that goes through the shell into a socket in the master, pour silicone into the gap through a funnel, and vents at the high points let the air out. A flange with M3 bolt holes and loose dowels holds the halves together, legs let it stand, and small bumps on the inside lock the cured silicone into the shell when you cast. A wick option lines up a wick hole with the pour channel for candles. The page shows how much silicone it needs next to a poured box mold.
• Two-part block — a rigid mold you cast straight into, split on a plane along X, Y or Z, with pour spouts, vents and alignment keys.
• One-part open mold — its top is the plane you choose, so the cast gets a flat back there: soap, chocolate, coasters, concrete.

Before any of that, the mesh check repairs the model (welding vertices, closing holes, turning flipped faces, removing duplicates, merging overlapping shells) and says what it changed; a voxel rebuild handles anything still broken. The undercut map marks where a rigid mold would lock — including spots hidden behind other geometry, found with a ray test — and “fill undercuts” adds material down to the parting plane so the mold releases, with undo.

New to silicone? How to make a silicone mold from a 3D print covers box, two-part and shell molds, how much to mix, and sealing the print.

Head-to-head

When Meshcast is the right choice

• You need a mold type splicestl does not make: a vase or planter with a core, a plaster mold for slip casting, a multi-cavity tray, or a press mold.
• Your master is complex enough that a three- or four-part shell demolds better than two halves.
• You want 3MF files with print settings, a warning when a part won’t fit your bed, or a guide library and community alongside the tool.
• You want the server to do the heavy work on a slow device.

When splicestl/mold is the right choice

• You make more than two molds a week, or sell what you cast, and don’t want a subscription.
• The model can’t leave your computer — a client’s master, an unreleased product, a scan of a person.
• The mesh is large or detailed: it is used as it is, not reduced.
• You want a silicone shell, a two-part block or an open mold, made without an account, and the repair and undercut tools in the same place.

The honest assessment

Meshcast is the more complete mold product: more mold types, multi-part shells, nicer output files and far more teaching material, and the free tier is enough to try every mold type. splicestl/mold covers the three molds most people start with — and the silicone shell is the one that matters most for organic models — with no limits, no account and nothing uploaded. If your project needs a vase core, slip casting or a four-part shell, use Meshcast. If you want to make shell or block molds freely and privately, start with splicestl/mold; nothing stops you using both.