Additively Manufactured NdFeB Polyphenylene Sulfide Halbach...

Additively Manufactured NdFeB Polyphenylene Sulfide Halbach Magnets to Generate Variable Magnetic Fields for Neutron Reflectometry (osti.gov)

Highly authoritative article from 3D PRINTING AND ADDITIVE MANUFACTURING Volume 9, Number 4, 2022

"The Halbach array is the most efficient PM assembly and presents an attractive solution to the current magnet supply problem, where the internal magnetic field scales with the product of average magnetization and the logarithm of the ratio of the external and internal radii of the ring."
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NOTE that the bonding material polyphenylene sulfide (PPS) is a high performance plastic that can be used in both powder bed fusion AM and more commonly fused deposition AM.

From Wiki:

Maximum service temperature is 218 °C (424 °F). PPS has not been found to dissolve in any solvent at temperatures below approximately 200 °C (392 °F).^{[citation needed]}

An easy way to identify the compound is by the metallic sound it makes when struck.