Sofa, I think your futuristic concepts here are really sound, and interesting to look at because they have a nice grounding against some of today's machinery.
It would be beneficial for you to push them more out of the "sketch" stage tho, by tightening up more of your linework. Are you working these all digitally? If so, there are ways to use, or set up a default brush which will aid in keeping your lines in order. If not, just hit the 'ol ruler before scanning them in, although there are some disciplined "freaks" working today who can do this quite well, and at many size-scales using only their arm, and keeping their wrist straight during the drawing motion lol
From a coloring standpoint, most of your work here is dealing primarily with "flat-color" techniques. So, when working color in this way, and to add some more
punch to your concepts, it's essential for you to use any current understanding of how light/shadow affect the surface planes of an object, so that you can push more depth out of your base linework; otherwise you're work will come across as bland, or unfinished regardless of any colors used throughout.
Again, I really like your concepts, and I'm hoping you will stick around and start up a sketchbook as soon as you have more to show us.
