scad-build

This is a multi-STL OpenSCAD build system based around GNU make. It supports dynamic build targets, intelligent previews with user-defined part layouts, and autoplating to efficiently send the maximum number of objects that will fit your 3D printer build plate to your slicer, reducing the amount of work that goes into printing complex projects.

Requirements

• OpenSCAD 2021.01 or newer
• GNU make
• Python 3.9.x or newer and the command line version of prusa-slicer (only for autoplating)

Using scad-build

This repository is intended to be a template to base new projects off of; existing projects without a build system can be adapted to use scad-build too. The files in this repository expect to be copied into the root of your OpenSCAD project.

Importing

Once you have installed scad-build into the root of your project, import it into any SCAD file you want to export multiple STLs from with import <./build.scad>. Modify the path if build.scad is not in the same directory as your SCAD file.

Using build(id)

build() is a module that designates its children as a separate build unit; this will cause make to output an STL at out/scad_file/build_id.stl containing only the children in scope for the build(build_id) module in the file scad_file.scad. build modules exist at runtime, so they can be nested under other modules if desired, or generated dynamically. Note that for scad-build to work properly, everything that renders during a build should be scoped under a build() module. See the section on previewing below for information on how to render multiple items while designing.

While scad-build is running under make, the function building() will return true, and building(build_id) will return true if the current build unit for the openscad process has been called to handle build(build_id).

Children of build() can access the current build ID via the $build_id variable. If there is no build() parent, $build_id is the empty string.

scad-build only pays attention to the first build() module in a render tree; any instances of build() inside of build() will not be picked up by the build system.

Previewing

scad-build has three distinctive modes for the OpenSCAD runtime. The first is build() module discovery, which is an implementation detail. The second is build mode, where make calls openscad with a single build_id selected. The third mode is preview mode, the default mode when scad-build projects are accessed outside of make -- most relevantly, in OpenSCAD's UI for preview.

While previewing, the function previewing() returns true. This can be used to define modules that will render all of your STLs in the same view while you are designing them without interfering with building. See the preview_row() and preview_column() modules in build.scad for ready-to-go preview layout utilites that demonstrate how to use previewing() to generate your own layout.

Note that preview modules disable layouts and call children() when not previewing, because they expect to only render children wrapped in build(), and only the child matching the build_id will be rendered when not previewing.

Building (rendering)

Type make to start a build. Your STLs will end up in the out directory, in subdirectories named after the SCAD file used to build the STL. Each STL is named after the argument to its parent build() module.

Multi-process rendering

scad-build supports the standard make mechanism for multi-process/multi-core builds: specify -j# as an argument to make, where # is the number of processes (build units) you want to render simultaneously.

Autoplating

Ideal for complex 3D printing projects with many discrete parts, autoplating tries to pack the maximum number of STL files into your build volume. It requires Python 3.9.x and the command line version of prusa-slicer to be accessible.

Configuring

Autoplating requires you to create a .plateconfig file in your project root; this file should be added to your .gitignore, since it is specific to your 3D printer. Its contents should look like:

[plate]
size_x = <the x size (width) of your build volume in mm>
size_y = <the y size (height) of your build volume in mm>
spacing = <optional: the amount of space to leave between objects (default: 8mm)>

Running the autoplater

Type make autoplate. If you have written a .plateconfig and have all of the necessary dependencies, this should build your STL files if necessary, then populate out/autoplate with subdirectories representing each prepared build plate. Each subdirectory contains the STLs on that plate (more specifically, symbolic links to already built STLs to save space).

To slice a whole plate based off of the autoplater's suggestion, call your slicer like: prusa-slicer out/autoplater/plate0/*.stl, changing this command as needed if slicing other plate numbers or using Cura or another slicer.