Leather Dog Collar is crafted with Blacksmithing in Mabinogi. This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Blacksmith Companion.
How to get the manual
The manual is rank F and survives 30 uses; every crafting attempt spends one use.
Edern: Edern's blacksmith shop in Bangor (100 gold).
Iria Treasure Hunt Event (Back to School 2011): source of record.
Materials
Expect about 1 attempt per finished item (99.9% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
2× Fine Leather — fragmentation of Fine Leather Strap (or weaving byproduct)
1× Iron Ingot — refine from Iron Ore (common low-rank Refining output)
Finishing (once per item)
1× Thick Thread Ball — Hot-Air Ballooning reward (11-15 stars) or gift from Simon