Spark Leather Armor is crafted with Tailoring in Mabinogi (armor). This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Tailoring Companion.
How to get the sewing pattern
The sewing pattern is rank 7 and survives 30 uses; every crafting attempt spends one use.
Nora: Buy it from Nora at the inn in Tir Chonaill. (121,000 gold). No special requirement, just enough gold.
Walter: Buy it from Walter's General Shop in Dunbarton. (121,000 gold). No special requirements, just gold.
Effie: Buy tailoring manuals directly from Effie's shop at Qilla Base Camp in Port Qilla (121,000 gold). Standard gold purchase, no special currency needed
Galvin: Buy a pattern from Galvin's shop under the Observatory in Emain Macha. (121,000 gold). None beyond having enough gold.
Neid: Defeat Neid, the field boss that lives in Lake Neagh inside Abb Neagh.. Fought in the open field, no special pass needed, but it hits hard and works best with a group.
Materials
Expect about 5 attempts per finished item (20% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
5× Fine Leather — fragmentation of Fine Leather Strap (or weaving byproduct)
5× Common Leather — low-rank Weaving skill output
5× Tough Thread — weaving Thin Thread Balls
2× Iron Plate — refine from Iron Ingot (re-refining)
Finishing (once per item)
1× Fine Finishing Thread — Buy directly from any general goods NPC shop.