This mods allows access to trains/signals/stations earlier/cheaper in a PY playthrough.
Based of the code from https://mods.factorio.com/mod/py-early-trains

Changes
-- tank
RECIPE("storage-tank"):replace_ingredient("duralumin", {type = "item", name = "iron-plate", amount = 20}):remove_ingredient("lead-plate")
--locomotive
RECIPE("locomotive"):remove_ingredient("duralumin"):remove_ingredient("electronic-circuit"):remove_ingredient("intermetallics"):remove_ingredient("shaft-mk01"):remove_ingredient("gearbox-mk01"):remove_ingredient("brake-mk01")
-- wagons
RECIPE("cargo-wagon"):remove_ingredient("duralumin"):remove_ingredient("titanium-plate"):remove_ingredient("intermetallics"):remove_ingredient("brake-mk01"):remove_ingredient("shaft-mk01")
RECIPE("fluid-wagon"):remove_ingredient("titanium-plate"):remove_ingredient("duralumin"):remove_ingredient("intermetallics"):remove_ingredient("brake-mk01"):remove_ingredient("shaft-mk01")
-- rails
RECIPE("rail"):replace_ingredient("bolts", {type = "item", name = "iron-stick", amount = 4}):replace_ingredient("treated-wood", {type = "item", name = "wood", amount = 4}):remove_ingredient("solder"):remove_ingredient("steel-plate")
-- signals
RECIPE("rail-chain-signal"):replace_ingredient("electronic-circuit", {type = "item", name = "inductor1", amount = 2}):add_ingredient({type = "item", name = "small-parts-01", amount = 2})
RECIPE("rail-signal"):replace_ingredient("electronic-circuit", {type = "item", name = "inductor1", amount = 2}):add_ingredient({type = "item", name = "small-parts-01", amount = 2})
-- stations
RECIPE("train-stop"):replace_ingredient("electronic-circuit", {type = "item", name = "inductor1", amount = 5}):add_ingredient({type = "item", name = "small-parts-01", amount = 10})