I have a few mobile phones' structural designs in my mind and want to propose them for pitching. I need to create the designs on paper and then represent them like this:
If you have new geometric forms, you should build 3D models. You cannot make it by editing existing images if they do not exist. With 2D software such as Photoshop or Illustrator you must be a highly skilled draughtsman and software user to get new forms right.
In 3D modelling software you can experiment easily with different views, materials and structures. In 2D you must draw every view separately. 2D is theoretically enough for every image on paper but to reach the needed skill level one must practice years.
Start to learn 3D modelling. I guess you can get something worth to show in few months instead of years.
If you do not need 100% realistic materials, practical manufacturability nor plausible functionality you can get something very quickly. See this Phony Jailman 2020. One can draw it in twelve minutes after learning some most basic 3D skills