TL;DR
Construction bots should be in progressive tiers rather than as a single "blueprint everything" tier that radically alters gameplay upon achievement.Why ?
Today, most players follow a fairly common practice in any playthrough: they rush a "bootstrap" base that gets them to robotics. After they've achieved robotics, they enter the "construction robot epoch" of the game. They become super-productive and immediately expand to a much larger factory using blueprints and construction bots, often deconstructing major portions of their original bootstrap base, if not all of it.The difference between non-blueprint and blueprint play is enormous. The former is characterized by oneous repetition of building tasks while the latter virtually eliminates these same onerous repetition tasks. The 0.17 copy & paste additions improved this situation somewhat in the early game, but ironically these streamline the "fun" design part of the early game while still requiring lots of repetitive clicking to fill in the ghosted structures.
What ?
I propose that by offering weak tiers of construction robots earlier in the tech tree, a small set of the boring repetitive will be diminished without completely removing manual building from the early game. Lower tiered bots would have stronger restrictions on what entities they can build, with the lowest tier being even as simple as just belt and power pole. A research upgrade would then offer underground and splitters, another would offer inserters and gray assemblers. Later tiers would offer both more functionality and higher ingredient requirements until you get the full construction bot as we have today some time in the midgame.These bots would also expand creative gameplay by constraining early play to blueprint with tighter constraints. This would motivate a wider class of "simple" blueprints in the early game. It would help a user sketch out big basic belt spacing and balancer structure while leaving assembler and inserter details to be filled in, as some rail blueprints are often used. This allows the player to progressively eliminate the burden of manual repetition without making the game too easy all at once and without "wiping out" the manual tasks as bots do today. It motivates a more continuous evolution of gameplay style rather than a robotics rush followed by a radical shift.
All this said, I am sensitive to the fact that the game can be made less fun by automating too much or by making it less difficult. This approach focuses on progressively phasing out tasks that are time-consuming but not actually challenging. It is also possible that today's full 0.17.69 construction bot could come later in the game so that there's a both a "give and take" to this rebalancing of difficulty and achievement.
Programmer's Details
This is not possible today as a Lua mod.The Lua API does not expose much of the construction bot's behaviour. It is mostly in fast C++ code since bots carry single items and get quite numerous in the late game. That said, (C++ hat on) I believe an economical way of implementing this is to simply assign an integer "complexity" number to the construction-bot entity itself, and to require construct-able entities to declare a corresponding integer. A bot would legally build a ghost if its complexity tier matches or exceeds that of the ghost. This eliminates the need for costly Lua table lookups or list-searching in related prototypes. It also provides the option of introducing this as a research upgrade on existing bots, rather adding more prototypes (and hence more items for the already-crowded build menu). But these are details for further digression.
Also: kovarex, klonan, rseding and friends: if you hire me, I will write it. And perform any other C++/Lua coding tasks you may require.