[uncatastrophic]

do you want to artifice but nothing below t2 is actually worth anything? do you want to speedrun it in a day despite that not mattering? then this guide is for you.

Tier 5
The only real option here is the Copper Shuriken.
Copper Shuriken: 5 Copper, 100 Energy -> 100 EXP
~0.7 EXP/Energy (1 without mining)
Tier 4
Here you gain choices: the Iron Shuriken lets you use much easier to obtain iron, while the Adamantite Chestplate is efficient if you already have lots of adamantite to spend.
Iron Shuriken: 5 Iron, 100 Energy -> 150 EXP
~1.03 EXP/Energy (1.5 without mining)
Adamantite Chestplate: 15 Adamantite, 100 Energy -> 250 EXP
~1.06 EXP/Energy (2.5 without mining)
Repair: 250 Energy -> 200 EXP
0.8 EXP/Energy
Tier 3
The whetstone of spamming arrives here, which can be made very cheaply for good experience. Steel shurikens stack and don't need adamantite, and the Steel Gloves make decent pre-150 weapons.
Whetstone: 2 Iron, 1 Adamantite, 100 Energy -> 250 EXP
~1.97 EXP/Energy (2.5 w/o mining)
Steel Shuriken: 5 Iron, 100 Energy -> 200 EXP
~1.38 EXP/Energy (2 w/o mining)
Tier 2
Here we unlock gear people might actually want to use. You can definitely get to T1 making only useful items from here on out, but the efficiency also rises if you use rarer materials. If you go for your Ultra Mythril Legs and such now, you'll get a lot of experience from that.
Mythril Chest: 15 Mythril, 100 Energy -> 750 EXP
~3.19 EXP/Energy (7.5 w/o mining) Note: Bluesteel chest (6 Iron, 9 Blue Mercury) is as efficient.
Mythril Legs: 3 Mythril, 100 Energy -> 375 EXP
~2.95 EXP/Energy (3.75 w/o mining)
Gold/Silver/Mythril Ring: 3 Iron, 3 Orichalcum/Blue Mercury/Mythril, 100 Energy -> 500 EXP
~3.25 EXP/Energy (5 w/o mining)

If you make these things, you can reach T1 Artificer pretty fast! Personally, I'd recommend spamming mythril legs until an ultra for that t2 grind if you're taking the "already rich" path with a good anvil, as ultra mythril is very useful.