Catwalks: Walkways for Steel, Aluminium, and Wood
A Steel Catwalk costs five 
Steel Rod and three 
Steel Scaffolding Slab and gives you six blocks of industrial walkway, which makes it one of the cheapest ways to get a railed floor across the top of a factory. Immersive Engineering builds catwalks in three materials, and all three share the same recipe shape.
The recipe
Every catwalk uses the same pattern: three rods across the top row, one rod at each end of the middle row, and three scaffolding slabs along the bottom. That returns six catwalks.
- Steel Catwalk - five Steel Rod and three Steel Scaffolding Slab
- Aluminium Catwalk - five
Aluminium Rod and three 
Aluminium Scaffolding Slab - Treated Wood Catwalk - five
Treated Stick and three 
Treated Wood Slab
Stairs use a diagonal arrangement of the same two ingredients - three slabs stepping down with two rods behind them - and return four catwalk stairs of the matching material.
Sourcing the ingredients cheaply
The two inputs are both cheaper than they first appear.
Rods come from the Metal Press with a rod mould, and one ingot yields two rods for 2,400 Flux. That halves the metal cost against making them any other way, so a press pays for itself the moment you start building walkways in bulk.
Scaffolding slabs come from scaffolding blocks. One 
Steel Scaffolding cuts into six slabs, and scaffolding itself is six blocks from three 
Steel Ingot and three Steel Rod. Working the chain through: three ingots and three rods make six scaffolding, which cut into thirty-six slabs, which is enough bottom rows for twelve catwalk crafts, or seventy-two catwalk blocks.
Treated wood is the budget material. Treated Stick and Treated Wood Slab both come from treated planks, so an early base can floor an entire machine gallery before a single steel ingot exists.
Choosing a material
The three are mechanically interchangeable, so pick on appearance and on what you already stockpile:
- Steel reads darkest and matches steel scaffolding, machine casings and the heavy multiblocks.
- Aluminium is pale grey and pairs with aluminium scaffolding, which suits lighter builds and rooftop runs.
- Treated Wood matches the wooden-era blocks, the crude blast furnace and treated wood scaffolding.
Building with them
Catwalks are the horizontal partner to scaffolding's vertical runs. The usual arrangement is scaffolding columns carrying the load, catwalks bridging between them, and catwalk stairs joining the levels. Because a catwalk is built on a scaffolding slab, a run of catwalk lines up flush with a scaffolding slab floor, and the two can be mixed in the same plane without a visible seam.
For a multi-storey factory, work out the vertical layout first: scaffolding towers at the corners, a catwalk deck at each machine level, and stairs at one corner rather than ladders. Where you do want a ladder, the 
Scaffold Covered Ladder in steel or aluminium sits inside a scaffolding block and keeps the run flush with the wall.
Covers the mod's in-game guide topics: