Cut and pasted from that hopelessly slow wiki:
The Electric Blast Furnace is a 4-block high hollow 3x3 box. The top layer is constructed from 8 Heat Proof Machine Casings around one
Muffler Hatch. The Muffler Hatch must be facing up and must be facing an air block.
The two hollow middle layers are constructed from 16
Heating Coils.
The bottom layer is more mixed, and must contain the following:
The bottom layer may also contain 1
Input Hatch, used to input fluid Oxygen gas for some recipes.