Terra Diamond-shaped Leather Boots is crafted with Tailoring in Mabinogi (shoes). 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 5 and survives 30 uses; every crafting attempt spends one use.
Walter: Buy it from Walter's General Shop in Dunbarton. (72,200 gold). No special requirements, just gold.
Granites: Buy a pattern from Granites's general store in southwest Filia. (72,200 gold). Elf-allied humans get a discount, other races pay full price.
Effie: Buy tailoring manuals directly from Effie's shop at Qilla Base Camp in Port Qilla (72,200 gold). Standard gold purchase, no special currency needed
Galvin: Buy a pattern from Galvin's shop under the Observatory in Emain Macha. (72,200 gold). None beyond having enough gold.
Materials
Expect about 8 attempts per finished item (13% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
3× Fine Silk — weaving on a loom, low-mid rank
3× Fine Leather — fragmentation of Fine Leather Strap (or weaving byproduct)
3× Tough Thread — weaving Thin Thread Balls
Finishing (once per item)
1× Fine Finishing Thread — Buy directly from any general goods NPC shop.