8 recipes · 9 tiers · 4 gathered materials
Everything the hideout needs to make Polyethylene Base, read left to right: the goal is on the left, the things you gather are on the far right, and every dashed box between them is one bench recipe. 19 recipes left out: each needs something already further along the chain, so it is not a way of making this. 55 links cut where two base materials convert into each other — a loop is not a step toward anything.
Gathered materials 4
Craft graph
Oil gather ×4
Reagents craft ×5
Huge Artifact Fragment gather 
Strange Artifact gather 
Aluminum Powder craft ×7
Bottle of Pure Water craft ×3
Methane craft ×3
Petroleum Coke craft ×2
Saltweed Pulp gather ×50 2
2
Thermal Mixture craft ×10
Electric Mixture craft ×2 3
3
3
Ethylene craft ×5
Aluminum craft ×5
Chlorine craft ×4 3
2
Ethyl Aluminum craft 
Industrial Solvent craft 3
Polyethylene Base goal