Merged Furnaces

Fuse several furnaces into one and turn it into a smelting beast.

Fabric Minecraft 26.1.2 Java 21+ Client + Server

Overview

A Fabric mod for Minecraft 26.1.2 that adds a single block, the Merged Furnace, which evolves through 10 levels. Every level unlocks more slots, more speed, and ultimately better fuel efficiency.

Parallel smelting

Up to 5 items cook at the same time, each with its own independent progress arrow.

Stacked fuel

Up to 5 chained fuel slots that burn one after another. Load a stack in each and forget about refueling for hours.

Level preserved

Break it and place it again - keeps its exact level. No upgrade progress is ever lost.

Visual identity

Each level shifts the stripe color on the block and the item following a "heating up" progression.

Crafting

The base Merged Furnace is crafted with 4 vanilla furnaces in a 2×2 pattern on the crafting table. It starts at level 1.

How to level up

With the Merged Furnace placed in the world, hold a vanilla furnace, blast furnace or smoker in your hand and right-click the block. Each upgrade:

Consumes the furnace from your hand (in survival).
Plays the anvil sound as upgrade feedback.
Bumps the level by 1 (up to 10).
Changes the stripe color of the block instantly.
Sends a chat message confirming the new level.

Level progression

Upgrades come in two phases. Levels 1-5 multiply speed and add fuel slots. Levels 6-9 add input + output pairs for parallel cooking. Level 10 caps it with a final speed + fuel efficiency bonus.

Level	Color	Input	Fuel	Output	Speed	Efficiency
1	Blue	1	1	1	1×	1×
2	Cyan	1	2	1	2×	1×
3	Green	1	3	1	3×	1×
4	Orange	1	4	1	4×	1×
5	Red	1	5	1	5×	1×
6	White hot	2	5	2	5×	1×
7	Light cyan	3	5	3	5×	1×
8	Magenta	4	5	4	5×	1×
9	Violet	5	5	5	5×	1×
10	Gold	5	5	5	6×	+25%

The interface

The GUI is laid out vertically like a real chimney: fuel burns at the bottom, the item cooks in the middle, and the result rises to the top slot. Slots locked by the current level show a red padlock. Each input has its own progress arrow that fills from bottom to top.

Top row: 5 result slots (output).
Vertical arrows: per-slot cook progress.
Middle row: 5 input slots (items being cooked).
Bottom row: 5 fuel slots. The active slot shows an animated flame on top.
Top-right corner: "Lv. X / 10" indicator.

Under the hood

Parallel cooking

From level 6 onwards, every input slot processes its smelting recipe independently. Each slot has its own timer, so you can run 5 different recipes at once (iron + gold + food + glass + sand, for example).

Fuel drains proportionally to the number of active items: if 3 items are cooking, burn time decreases by 3 units per tick.

Level 10 efficiency bonus

Level 10 introduces two subtle but stacking benefits:

Effective fuel drain per tick is max(1, N-1), where N is items cooking. Cooking 5 items costs you what 4 would.
Every fuel piece ignites with a +25% duration bonus.
Base smelting time drops to ~33 ticks (20% faster than the level 5 cap).

Level preservation on break

The block is mined with any pickaxe (registered as a pickaxe tool block) at the same speed as a vanilla furnace. On break:

Drops the full inventory contents (inputs, fuels and outputs).
Drops a Merged Furnace item with its level saved. The item icon already shows the matching stripe color.
When placed back, the block immediately appears at its original level - no level 1 flash - because the component is read at placement time.

Technical details

Block & BlockEntity

Block state with facing, lit and furnace_level (1-10) properties. The BlockEntity keeps its level in sync with the state through the server tick.

Custom data component

merged_furnaces:furnace_level (Integer): read by both the item model (via minecraft:select) and getStateForPlacement when placing the block back.

block_entity_data

Same vanilla mechanism shulker boxes use: the dropped item carries a FurnaceLevel tag that is applied to the newly created BlockEntity during placement.

Procedural GUI

The entire panel is drawn with primitives (fill / text on GuiGraphicsExtractor), no PNG background. Flame and arrows rendered pixel by pixel.

Installation

Make sure you have Fabric Loader 0.19.0 or newer for Minecraft 26.1.2.
Install Fabric API 0.149.1+26.1.2 (or a newer compatible release).
Drop merged_furnaces-1.0.0.jar into the mods/ folder on both the client and the server.
Restart and craft a Merged Furnace with the 2×2 recipe.

The mod is client + server: both sides need the JAR. The server handles block logic and smelting; the client renders the GUI, textures and the item model.

Merged Furnaces · vicxelcode · Built for Minecraft with Fabric

merged-furnaces