STLTools v1.0.1: Free Open-Source Parametric STL Generator

STLTools is a free, open-source parametric STL generator for drones, RC planes, robotics, and the workshop. Pick one of 3,661 ready-made designs from 54 generators, change any size, see the print time and filament for your printer, and download watertight STL files that are already in print orientation. It runs as a small local server on your own computer. Nothing is uploaded anywhere.

This post covers the public release, v1.0.1 (November 6, 2026), on the main branch of opsecfreak/STLTools (Apache-2.0). There is also a separate MTS personal edition on the mts-personal branch with the shop’s own parts list; that is a pre-release line, and it is not what is covered here.

What it does

Designer. Every size is a field. Simple mode shows the main sizes; All settings shows every wall, clearance, and screw. The live preview rebuilds the part as you type.
3,661 presets. Hand-made designs plus about 3,200 checked size series: clamps per tube size, spacers per bolt and length, gears, pulleys, 32 bearing sizes, cell holders, drawers, and more. Every series preset is generated and checked before it ships.
Browse and organize. Filter everything by type, tab, category, generator, tags, size series, measuring status, and your own Collections. Favorites, and global search (/) with a query syntax (tubeOD:16, teeth>=30, tag:esc).
Assemblies. Multi-part designs shown put together or as a print plate: servo pan-tilt gimbal, brushless 2-axis gimbal frame, drawer unit. Projects can place any parts together in 3D.
Print estimates. Time, grams, metres, and cost per part and in total, plus a bed-fit check, for your printer profile. Sovol SV07 and generic profiles are included; you can add your own.
Projects. Parts lists with quantities, notes, and printed checkboxes, one-ZIP download with a parts list, export/import between computers.
My Parts. Your own parts list (Owned / Confirm / Planned) with sizes and “needs measurement” flags; filter presets to what you own. Start from the example list or import your own components.json.
No guessed sizes. Sizes nobody measured stay empty, and Generate waits until you type them. Datasheet values are highlighted to check.
STL Files. Import STL files you already have: view, estimate, tag, add to projects.
Printers (view only). Status, temperatures, progress, files, history, and webcam of Klipper / Moonraker printers (Mainsail, Fluidd, Sovol SV07) on your LAN, plus G-code upload that never starts a print. No control endpoints exist in this release.
CLI and API. stltools gen and stltools preset for scripts; an HTTP API for everything the UI does.

Units are millimeters, because slicers read STL as mm. All parts print without supports, each in its print orientation.

Designer: type a size, watch it rebuild

Designer: Pi 5 case, live 3D view, print estimate

The Pi 5 case above is a good example of the workflow: set the sizes, check the live 3D view and the per-part time and filament estimate, download the STL.

TF-Luna bracket with fields to check and the 3D view settings

Datasheet sizes are flagged for checking instead of silently trusted, and the 3D view has its own settings (shaded / edges / wireframe / x-ray, layer cut, bed outline, PNG export).

A part with no measured size: fields stay empty until measured

Unmeasured sizes stay empty. The app will not invent a dimension for a part that has to fit real hardware.

Tooltip with range, default and setting name

Every setting has a tooltip with its range, default, and setting name.

Browse 3,661 presets, or search for exactly what you need

What it makes

54 generators, grouped by tab. Every size is a parameter: tube OD and ID, clearances, wall thickness, bolt size (M2 to M5), hole patterns, angles.

Shop (841 presets): drawer unit (assembly), spool holder, drill guide, stacking bins, parts box, holder block, hook, tool rack, label card, fit-test coupons for heat-set inserts, holes, and press fits.
Planes (247): RC wing (wingspan, chords, sweep, washout, spar tubes, ailerons / elevator / rudder cut as separate parts, servo pocket, wire channel), control horn, servo mount, pin hinge, firewall mount, fuselage former, RC wheel.
Quadcopters (495): printed drone arms, multirotor frames (3 to 8 arms), motor mounts, prop guards, landing legs, repair-stand bench cradles, plus mounts for ESCs, receivers, VTX, flight controllers, GPS posts, batteries, lights, and wires. Yuneec Typhoon H480 / H520 bench and gear-leg parts are in there too (measure first).
Accessories (986): cell holders (18650 / 21700 / 26650 / AA / AAA), tube clamps (split, mount plate, saddle, parallel, cross, snap-on, two-piece, collar), tube joints, tube caps, spacers, GPS masts, antenna mounts, camera mounts, FC adapters, soft grommets, damper plates.
Robotics (1,092): shaft supports, servo and brushless gimbals (assemblies), gears (spur, helical, herringbone, rack), GT2-style pulleys, NEMA stepper mounts, bearing blocks, shaft couplers, link bars, knobs, enclosures, Raspberry Pi cases, sensor brackets (TF-Luna, TFmini), lidar mounts, extrusion brackets, motor clamps.

Assemblies and projects

Servo pan-tilt gimbal assembly with per-part print estimates

Project assembly view with item positions and per-part estimates

Project with parts, quantities, estimate and export

Assemblies show parts put together, with time and grams per part. Projects hold parts lists with quantities, and export everything as one ZIP with a parts list.

Printers: view-only Klipper monitoring

Settings: connect and test a Klipper printer

Printers page: status, temperatures, files, webcam (view only)

The Printers tab talks to Moonraker over your LAN: state, progress, layer, print time, time left, filament used, nozzle and bed temperatures, G-code file list with thumbnails, print history, and webcam snapshots. G-code upload always sends print=false. In v1.0.1 this is view-only by design: there is no start, pause, resume, cancel, or G-code send. Estimates can use your printer’s own Klipper limits.

Import, dark mode

Download and run v1.0.1

Open the v1.0.1 release and download the file for your computer. Each desktop package includes Node.js 22.12.0, so nothing else needs installing.

Windows 10/11 (64-bit): stltools-1.0.1-windows-x64.zip
Mac, Apple chip (M1–M4): stltools-1.0.1-macos-arm64.tar.gz
Mac, Intel chip: stltools-1.0.1-macos-x64.tar.gz
Linux PC (64-bit): stltools-1.0.1-linux-x64.tar.gz
Raspberry Pi 4 / 5, 64-bit OS: stltools-1.0.1-linux-arm64.tar.gz
Raspberry Pi, 32-bit OS: stltools-1.0.1-linux-armv7l.tar.gz
Any system with Node.js 18+ already installed: stltools-1.0.1-any-os.zip

Unpack it and read README-FIRST.txt. Start it with Start STL Tools.bat (Windows), STL Tools.app (macOS), or ./start.sh (Linux / Pi). On Home, press a Make something button (for example Tube clamp), set the sizes, press Download STL. Verify a download by comparing its SHA-256 against SHA256SUMS.txt. Full steps: docs/INSTALL.md.

With Node.js 18+ already installed, the npm package is the quickest way:

npm install -g https://github.com/opsecfreak/STLTools/releases/latest/download/stltools-1.0.1.tgz
stltools app

Why this matters for GPS-denied builds

GPS-denied navigation is a sensor-mounting problem as much as a software problem. A visual-inertial odometry stack needs a camera rigidly mounted with a known offset from the IMU. A lidar SLAM setup needs a level, vibration-isolated lidar plate. Optical flow needs a downward sensor with a clear view and a rangefinder beside it. Every one of those is a printed bracket, and every one has to fit the exact airframe, tube, and board you are flying.

That is what STLTools is for on a build like this. The generators cover the parts a GPS-denied stack bolts onto: GPS masts, lidar mounts, sensor brackets (TF-Luna, TFmini, XIAO boards), Raspberry Pi cases for the companion computer, component mounts for flight controllers, ESCs, and receivers, antenna mounts, and camera mounts. Type in the measured sizes, print the bracket, and the sensor goes where the estimator thinks it is. The “no guessed sizes” rule matters here: a VIO camera mounted 5 mm from where the calibration file says it is will cost you more debugging time than the print ever saved.

MTSUAV

Research

Site

STLTools v1.0.1: Free, Open-Source Parametric STL Generator for Drones, RC Planes, and the Workshop