simsles

Firstly, I would ditch the motor and the large wheels. Neither is necessary on a commuter bike.
Your bike will need to fold neatly, be light and of simple construction.
If you have a chain make sure that it is enclosed within the fold.
The bike should roll on one of the road wheels when folded, so that it is only carried on steps or stairways. You should not need additional trolley wheels then, and the weight is less important.
Over the years, there have been hundreds of designs of folding bike. They all have their faults. Check them out.
The perfect folding bike has not yet been invented. Perhaps it never will be, since compromise is the name of the game.
Good luck, you have real challenge here.