Welcome to Furnace Mk2
This mod is a *fairly* simple extension of the vanilla furnace. The primary intention is solving the issue of sacrificing experience when you set up automated smelting; I love connecting three hoppers to my furnaces but missing out on all that experience sucks.
The mod intends to stay within a defined design scope and prioritizes quality over quantity. Functions and features should be fairly self explanatory through the use of tooltips. Features include increasing the speed, fuel efficiency, and experience output of the furnace, and an item to manage the experience produced (and player's experience).
It may seem like there is a lot going on in the inventory, but it is designed to guide you through using it; empty slots indicate what they are, and areas of interest have tooltips that offer some added information. JEI integration is included out of the box and uses the JEI-supplied vanilla furnace and fuel entries.
While there is built-in experience storage implemented in the Furnace Mk2, placing an Attuned Crystal in the bottom-right slot will ensure that the crystal's capacity is continuously topped up (and it's quite a bit more than the furnace itself).
Clicking the crystal removes experience from itself to give to the player, and shift-clicking transfers the player's experience to the crystal. The crystal holds 10,000 experience which from 0 is just over 63 levels.
It also makes a sound with a pitch that's influenced by the capacity which is pretty neat.
The mod is currently in beta, let me know of any bugs or issues that occur and ensure that you're backing up/saving worlds before making any changes to the mods you use!