Dear student,

Actually you can find the soft copy of the study materials for NID on the internet. The best study materials for NID are :-

NID DAT book by R.S. Aggarwal (aptitude section) NID Workbook

Design drawing by Francis D.K.Ching NID (B.Des.) Entrance Books and Test Series

Basic Rendering from Robert W.Gill Guide for NID

NID Mock Test Series Success Master- NID entrance Examination

So, these books you can find on the internet and can download the soft copies of them.

Also check out the following link to know more about NID study materials :-
https://design.careers360.com/articles/nid-dat-study-material