Revenant Insight Guard Cylinder is crafted with Blacksmithing in Mabinogi (shield). 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 7 and survives 30 uses; every crafting attempt spends one use.
Gilmore: general shop owner in Bangor, sells them at his counter (200,000 gold).
Materials
Expect about 4 attempts per finished item (25% average progress per attempt). Per-attempt materials are consumed on every attempt; finishing materials once per item.
Each attempt uses
1× Silver Ingot — refine from silver ore. Mine it in Barri Dungeon or north of Tory Ravine
1× Mythril Ingot — refine from mythril ore. Barri Mythril Mine/Advanced, or L-Rod ore deposits
3× Mythril Plate — re-refine from Mythril Ingot
1× Vengeance-Imbued Alchemy Crystal — Hard Tech Duinn missions drop
Finishing (once per item)
3× Gold Ingot — refine from 5 Gold Ore
5× Large Nail — hit props (lamp posts, signs, statues) or common low-level monster drops
3× Tough String — weaving Thick Thread Balls
1× Misty Red Gem — Tech Duinn hard difficulty mission drop