I wrote a small snippet of code.
If you select construction points and copy-paste the code snippet into the Ruby Console and hit Enter… it will create a curve according the cpoints z-cordinates order.
You can Undo it.
(No warranties, use your own risk as usual 
)
module Dezmo
module JoinCPointsZ
extend self
def join_cps(cps, ents)
sort_by_z = cps.sort{|a, b| a.position.z <=> b.position.z}.map(&:position)
ents.add_curve sort_by_z
end
def run
model = Sketchup.active_model
entities = model.active_entities
sel = model.selection
cps = sel.grep(Sketchup::ConstructionPoint)
return "No ConstructionPoints selected" if cps.size < 2
model.start_operation("Join CPoints by Z cords", true)
join_cps(cps, entities)
model.commit_operation
end
end
end
Dezmo::JoinCPointsZ.run
