How I built a tool that converts SVG files into 3D letter fabrication files (STL + DXF)

The problem

Every time a client wanted dimensional letters — for a sign, an
installation, a storefront — I hit the same wall.

Either I had to hire a 3D modeler, or spend hours in Blender
manually extruding paths, fixing normals, and setting up tolerances
for the acrylic slot.

Neither option was good. Hiring someone adds cost and back-and-forth.
Blender works, but it's slow and overkill for something that's
essentially a parametric operation on a 2D shape.

So I built FacLet3D.

What it does

You upload any SVG file — a typeface, a logo, any vector shape — and
the app generates:

STL files for the shell and base (ready for 3D printing or CNC)
DXF file for the acrylic face

You control:

Wall thickness
Base structure (outer wall, inner wall, heights)
Acrylic slot dimensions
General tolerances
Live 3D preview in the browser

No CAD knowledge needed. No Blender. No modeler.

How it works under the hood

The core challenge was parsing arbitrary SVG paths — including
compound paths, holes, and nested shapes — and turning them into
watertight solids with consistent normals.

SVG paths can be messy: overlapping subpaths, mixed winding orders,
self-intersections. Getting clean geometry out of arbitrary user input
required a lot of edge case handling.

The base and shell are generated as separate STL files so they can be
printed independently or assembled. The acrylic DXF is offset inward
by a configurable amount to account for laser kerf.

Who it's for

Graphic designers who want to hand off production-ready files without learning CAD
Signage makers and print shops
Makers with 3D printers who want to fabricate dimensional lettering