Here is a simple method to build Scratchbuilt stairs or ladders in any scale width & length ,repeatedly the same by making a jig out of pvc & card.
Draw the stairs shape on card or thin mdf.
Cut using this tool enough 30 to 45 deg teeth.
Glue them on the sketch.
Glue support sides
Measure & cut enough pvc or sprue peices ( texture steps with pliers)
Insert in jig.
Glue & bob or george is your uncle 😁😁😁
You can cut V notches in the bottom vertical ones so they can be glued to a larger horizontal peice for stability or glue it to a square mesh textured base
Go forth & multiply.
Thanks for your comments.