How to Get Twine in Pokémon Pokopia — Spinarak Litter Guide
Twine is a crafting material needed for building Pokémon Centers in Pokopia. Learn how to attract Spinarak and collect Twine from its Litter specialty.
by Insider Gaming
All Twine Sources

There are three ways to get Twine: use the Cut move on spider webs and textile garbage found in Rocky Ridges and other areas; collect drops from Bug-type Pokémon with the Litter Specialty (Spinarak, Ariados, Larvesta, and Volcarona); or purchase from the PC Shop in limited quantities.
How to Attract Spinarak

Spinarak spawns in Yellow Tall Grass. Create Yellow Tall Grass by placing a Smooth Rock near regular grass, or by placing Dry Field Grass blocks. Once Spinarak moves in, it will periodically drop Twine near its habitat — similar to how Combee drops Honey.
What Twine Is Used For
Twine is needed for Ditto Flags (to claim huts or houses as your home), furniture like awnings, chairs, and sandbags, and for habitat creation. The Bleak Beach Pokémon Center requires 10 Twine alone.