It is indeed annoying to have to place or buildings and conveyors strictly from the engineers perspective. it is okay at the start of the game but get really annoying later on when you have huge stacked conveyor belts and need to change something around that. usually you have no good point to stand on from which you can see and do the stuff you want and thus must build a lot of temporary foundations/walkways/watchtowers first. jetpack helps a little but it cant stand still in the air so it's useless for precision construction.
The obvious solution would be a small quadcopter like drone equipment that can stand perfectly still in the air. it should be a normal equipment item that is launched when used and switches camera to the drone. while viewing through the drone camera the engineer should be able to fully construct and deconstruct buildings as usual (however using the engineers inventory, not the drones). therefore it should have only limited operation radius around the player - leaving it will disable the drone and let it crash. furthermore the drone would be unable to pick up anything itself (at least not the basic drone variant). it would have an additional hotkey to immediately return to the player and switching the camer back to the engineer.
additionally as the drone would be just as invaluable for scouting (locating hard drives/power slugs) it would make sense to have an advanced version with the scanning tool incorporated. furthermore the game could add birds that are passive towards the player but attack drones in order to make exploration more difficult in some areas.
the drone should become available at tier 2 or 3. there should be either advanced drone variants later on or it should have an own limited inventory for equipment slots where upgrades can be placed in (e.g. scanner, improved radio range and other range upgrades, nobelisks, grappling arm, fuel).