Rosemary Gloves is crafted with Tailoring in Mabinogi (gloves). 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 4 and survives 30 uses; every crafting attempt spends one use.
Fishing in Avon: Fish in the submerged part of Avon for a rare pattern catch.. Requires an Avon Feather to reach Avon.
Sources that no longer exist: New Year Gachapon.
Materials
Expect about 20 attempts per finished item (5% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
1× Ice Silk — Obtained from a Festia Commemorative Gift Box.
1× Ice Fabric — Rare drop from Snow Troll, Bran, or Grim Reaper in Advanced Theater Missions.
2× Finest Leather Strap — weaving rank 3-1 on a spinning wheel
Finishing (once per item)
2× Finest Finishing Thread — Buy directly from any general goods NPC shop.