Celtic Dowra Aces is crafted with Hillwen Engineering in Mabinogi. This page lists everything needed to make it, checked against the game as it exists today. The interactive planner lives in the Hillwen Companion.
Recipe availability
Celtic Dowra Aces is a rank 4 Hillwen Engineering recipe with a best success rate of 54% at rank 1 and dan ranks.
Materials
Each craft uses
15× Hillwen Alloy
2× Energy Converter
1× Emerald Fuse
4× Cleansed Mage's Gem — hard mode dungeon or Rabbie Phantasm Dungeon drop
6× Shattered Black Metal — drops from Advanced/Hardmode Uladh dungeons (e.g. Rundal Basic, Rabbie Advanced)
2× Deformed Ring Frame — Trade Memory Fragments to the Campfire Spirit for one.