Mitcad's bundled material dataset

This folder's materials.json contains material property data from the
material-properties dataset (https://github.com/KittyCAD/material-properties),
commit 61088092d5a90bcf4e0beee0c6a36783776a3a88, copyright the
material-properties contributors, licensed under the Apache License,
Version 2.0 (the LICENSE file in this folder).

The data was changed: the dataset's files (materials/*.json) were converted
into Mitcad's materials exchange format, one list of materials in the
dataset's own units (psi, lb/in3, degrees Fahrenheit, microinches per inch
and degree Fahrenheit). The materials were named after their file, material
and grade; the ultimate strength and the elongation were left out; the
minimum and maximum extruder and bed temperatures of the printing
materials were kept as the extruder temperature range and the midpoints of
the ranges as the extruder and the bed temperature. The values themselves
are the dataset's.

The values are typical values for the materials. Check them against the
supplier's data before relying on them.
