Mod moved! See here: https://mods.factorio.com/mod/SimpleCompress

This mod lets you compress and decompress iron, copper, uranium, stone and coal. 20 items into 1 dense cube of resource. You need at least blue assembler to compress, but you can decompress with machine or hand-crafting.

Cheaty? Maybe a little in the sense that to transport ores around your base you need 20 times less robots. But it comes at a cost of more logistics complexion. Very likely the use of this mod will increase your UPS and FPS.

Does not support ores from mods (such as bobs). Any other item to compress needs its own new mod, consider them as separate modules. This mod's whole purpose is to be simple and vanilla friendly, and with as few recipes as possible.

This is a standalone mod, but companies my other mod; Plate compress
https://mods.factorio.com/mods/Zaflis/PlateCompress

Changes:
0.17.0: Update for Factorio 0.17.
0.16.0: Update for Factorio 0.16.
0.15.5: You can smelt compressed resources with faster than normal but with minor loss.
0.15.4: Crafting times increased from 2 to 4 sec and added recipe.lua variables.
0.15.3: Compressed coal can be used as fuel but 20% less efficient than coal. No handcrafting for decompressing. DE translations by factoriomayo.
0.15.1: Fixed crash when trying to use compressed coal as fuel, and it can't be used as fuel anymore.
0.15.0: Factorio 0.15.x compatibility and added uranium ore.
0.14.2: Changed tech requirement from steel to automation 2.
0.14.1: Initial release.