Hi, Gina, Here are a couple of suggestions.  You’ll need to review them to see which is most appropriate for your students.  The first is Engineering is Everywhere, from the Museum of Science in Boston.  These are modules, created by the same team that developed Engineering is Elementary.
http://eie.org/engineering-everywhere/curriculum-units
The second is Engineering the Future: Science, Technology, and the Design Process.  This was also developed at the Museum of Science in Boston.  Although intended for ninth grade, it is also suitable for 8th graders.  It has four semester-long projects.  The first one, Jump Into Engineering, needs to be completed first, but the others—Design a Green Building, Design with Light and Sound, and Patent Your Vehicle Design—can be done in any order.  I confess to being the project director on this one.  We just spent three years updating it to fully support NGSS. – Cary
https://activatelearning.com/engineering-the-future/

Both of these men are portrayed as lone inventors.  Tony Stark is fictional, Edison is not.  So we can examine Edison's life to draw some tentative conclusions about how realistic the "lone inventor" vision really is.  In fact, Edison lead a large team of inventors at Meno Park, New Jersey.  One of those was Louis Latimer, a black engineer who made important contributions to the light bulb, and whose life is documented on the Internet.  This is  a rich opportunity for student research and discussion.