IC2 Coin (Industrial Credit) is a token currency spent at Trade-O-Mat and Energy-O-Mat machines in Minecraft Java 1.7.10 and 1.12.2.
Guide
Smelt 8 Iron Ingots in a furnace and mine Tin Ore (commonly found between Y=0 and Y=64 in IC2 worldgen) to smelt 1 Tin Ingot. Iron and tin are the only materials the Coin recipe needs.
Open a 3×3 crafting table, place the 8 Iron Ingots around the outer ring and the 1 Tin Ingot in the centre slot. The recipe outputs a stack of 8 Industrial Credits per craft, so 1 Tin always yields 8 Coins.
Build either machine from IC2 components and place it where buyers can reach it. Right-click while sneaking to open the owner interface, where only you can change stock and price.
In the Trade-O-Mat, load the item stack you want to sell and set how many Coins it costs. In the Energy-O-Mat, connect EU input and set the EU amount sold per Coin.
Any player right-clicks the machine, inserts the required Industrial Credits, and the machine releases the configured item stack or charges their tool/battery with EU.
The Coin recipe is unchanged between IC2 1.7.10 and IC2-Experimental 1.12.2.
Place 8 Iron Ingots around the outer ring of a 3×3 crafting table and 1 Tin Ingot in the centre slot. Each craft outputs 8 Industrial Credits, so 1 Tin Ingot always produces 8 Coins.
Only two IC2 machines use Coins: the Trade-O-Mat, which trades item stacks for a Coin price set by its owner, and the Energy-O-Mat, which sells EU energy for the same kind of Coin-based price.
The Trade-O-Mat lets the owner accept Coins from any player without being online. Coins also keep all vending machines on a server using the same standard token, which is more predictable than item-for-item barter.
Yes. Coins stack to 64 per slot like normal items, but each individual Coin has no fixed value. Worth is whatever the owner of a specific Trade-O-Mat or Energy-O-Mat sets per trade.
No. Industrial Craft 2 is a Java Edition mod for Minecraft 1.7.10 and 1.12.2 (via IC2-Experimental). Bedrock Edition does not support Java mods, so Coins do not exist there.
No. IC2 does not provide a recipe to convert Coins back into Iron Ingots or Tin Ingots, and they are not accepted by the standard furnace or IC2 Macerator as a source material.