Pure Fused Hillwen Alloy is crafted with Hillwen Engineering in Mabinogi. This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Hillwen Companion.
Recipe availability
Pure Fused Hillwen Alloy is a rank 3 Hillwen Engineering recipe with a best success rate of 96% at rank 1 and dan ranks.
Materials
Each craft uses
10× Pure Magic Crystal — Trade Bri Leith Obols for it at Leannan's shop in Murias.
5× Pure Strength Crystal — Craft it with Magic Craft from Awakened Strength Powder and Essence of Raw Force.
1× Enchanted Melding Agent — Buy from Leannan's shop in Bri Leith for 500,000 gold.