The idea is the mover inserter
The basic concept is pretty simple.
- Early robot powered by fuel that either moves on treads or walks.
Every second it can do one action if the action can't be done it tries to do the next pre-
programmed action without delay.
In one of 4 directions you can do one of five actions, move, pickup, drop, place/build, de-construct ( if you put in the instruction to place/build it will ask you on a pop up grid how exactly to place the building)
When putting in its instructions you can just put in a list of actions but you can also do the following.
- Put a number next to a action so that action is repeated a number of times(can select unlimited with 0).
Name and group actions and then set that group to repeat a number of times(there can be groups within groups)
can have conditions added to its actions or groups e.g pick up from left if inventory has less than 10 iron.
Being blocked from moving a direction or being next to a certain object can be used as a condition
has a quasi sixth type of action (activate X instruction group) that makes the mover start doing the actions from that group/part of the instruction list, this allows for even more complicated instructions if you think smartly about the condition and timing of this action
- building longs lines of belt, pipe, wall, concrete or rail, could be used to build other things but for most people it would be too complicated to be worth it.
clear trees and collect wood
De- construct large scale parts of your base/factory
As for the cost depending on the tech level I would say 1x filter inserter + 1x steel chest + 20x gears + 15 seconds
here is a terra bad picture I made on loosely how it might work
note that i have zero talent and i didn't finish the picture but that what you get