I'm working through the Quantitative Equity Portfolio Management book by Chincarini and Kim.
I'd like to build a basic industry-based fundamental factor model. As this is a pet project for pedagogical purposes, I don't have the money to spend on Barra's GICS classifications. I also understand that other industry classifications (SIC and NAICS) are fairly useless for factor models.
Is there a reasonable open-source or homemade alternative (using, say, k-means clustering or non-negative matrix factorization) to create my own industry factors for US equities?