Super old work! There are defiantly more... There are "some" of the drill concepts I came up with for codehatch's 2013 video game title Starforge. The process was thumbnail heavy and an odd job. I've had a lot of experience handling manual rock drills in construction (pay them college bills). Hitachi Hilti is the best, hands down. In then end they went for oversized chunky designs but its fun to revisit some old ideas. The T4 drill was designed prior to my arrival on the project. All of these designs were included in the Starforge digital art book.
No, I did not use any 3d software. Just perspective line drawing.