I’m not sure this is what you’re looking for, but a quick list might include: 

Aspects of Manuscript Culture in South India, ed. Jan Houben and Saraju Rath (Leiden: Brill, 2012).

Indic Manuscript Cultures Through the Ages: Material, Textual, and Historical Investigations, ed. Vincenzo Vergiani, Daniele Cuneo, and Camillo Alessio Formigatti (Berlin: De Gruyter, 2017).

D. B. Diskalkar’s old but useful Material Used for Indian Epigraphical Records (Poona: Bhandarkar Oriental Research Institute, 1979). 

Sanskrit studies lags far behind the study of print culture and book history, but Ulrike Stark’s An Empire of Books: The Naval Kishore Press and the Diffusion of the Printed World in Colonial India (New Delhi: Permanent Black, 2007) is a must-read for anyone interested in the subject in a South Asian context. One can easily imagine a similar study for the Nirnaya Sagara, Chaukhamba, Anandashrama presses or other major Sanskrit publishers. Finbarr Flood’s Objects of Translation is one of the high water marks for the theory of materiality and book culture in second millennium SA, albeit in a Persianate context. Alexander O’Neill at SOAS wrote a dissertation on pustakapuja in the Newar context and would surely have much to contribute on the materiality of the book in ritual contexts. There’s lots of stuff of manuscript cultures and practices of writing, as you note.

Best wishes,