A free app for Android, by Engineering Hub.
Engineering Drawing is a software designed to help you prepare for civil engineering exams. With it, you can practice plain scales, projective geometry, and many more. It’s a complete free app that provides you with everything you need to achieve a good score in the exam.
It includes a lot of topics that are indexed chapter-wise. So, you don’t have to go through the lengthy process of reading through the whole manual.
It’s designed to work offline. You can use it in your classroom or at home.